Class 10 Physics Chapter 9 Household Circuits

This quiz on ICSE Class 10 Physics Chapter 9: Household Circuits is designed to assess students' conceptual understanding and application of key principles related to the functioning of domestic electric circuits. It includes questions that test knowledge of essential components such as fuse, circuit breaker, earthing, switches, and wiring systems. The quiz also covers the practical aspects of series and parallel connections, safety measures in home circuits, and the role of live, neutral, and earth wires. Through a mix of conceptual, diagram-based, and real-life application questions, this quiz aims to reinforce theoretical learning and promote safe and scientific thinking about electricity usage in everyday life.

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Category: Types of Fuses

1. A fuse wire of radius 0.4 mm is used in a circuit. If the current rating of this fuse wire is 4 A, what will be the approximate current rating for a fuse wire of radius 0.8 mm? (Given: $\Delta T \propto \frac{I^2}{r^3}$)

a) 2 A

b) 5 A

c) 10 A

d) 16 A

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Category: FUSE

2. (A) A fuse wire is made of an alloy with a low melting point to ensure it melts and breaks the circuit when excessive current flows.
(R) The resistance of the fuse wire generates heat proportional to the square of the current, which causes the temperature to rise until the melting point is reached.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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Category: COLOUR CODING OF WIRES IN A CABLE

3. While inspecting a three-core flexible cable, you notice one wire has green insulation. Which wire is this?

a) Live wire

b) Neutral wire

c) Earth wire

d) Fuse wire

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Category: Advantages of connecting the appliances in parallel

4. Why are household appliances connected in parallel rather than in series?

a) Appliances share the same current in parallel.

b) Each appliance gets full voltage rating and works independently.

c) Series connection provides better energy efficiency.

d) Parallel connection reduces the total resistance of the circuit.

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Category: Circuit Diagrams for Connecting Appliances

5. What is a key advantage of using a ring system in house wiring?

a) It requires thicker wires for the main ring circuit.

b) All appliances must share the same fuse.

c) It increases the total current drawn from the mains.

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Category: HOUSE WIRING (RING SYSTEM)

6. In a house wired with the ring system, four appliances (a 100 W bulb, a 60 W fan, a 2000 W heater, and a 1500 W AC) are connected to the same ring circuit. The main fuse in the distribution box is rated at 30 A. If all appliances operate simultaneously, which fuse rating for the heater will ensure the total current does not exceed the main fuse limit? Assume a supply voltage of 220 V.

a) 5 A

b) 10 A

c) 15 A

d) 20 A

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Category: CIRCUITS WITH DUAL CONTROL SWITCHES (STAIRCASE WIRING)

7. In a staircase wiring setup using dual control switches, what happens when the switch $S_1$ is operated from the 'off' position?

a) The bulb remains off as $S_2$ is not operated.

b) The connection changes from 'bc' to 'ba', turning the bulb on.

c) The connection changes from 'ba' to 'bc', completing the circuit and turning the bulb on.

d) Both switches must be operated simultaneously to turn the bulb on.

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Category: Working Mechanism

8. A lever system has a mechanical advantage of 4. If an effort force of 50 N is applied, what load can be lifted?

a) 100 N

b) 150 N

c) 200 N

d) 250 N

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Category: Working Mechanism

9. In a heat engine, 2000 J of heat is supplied, and 1200 J is converted into work. What is the waste heat rejected?

a) 500 J

b) 700 J

c) 800 J

d) 900 J

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Category: Transmission of Power from the Power Station to the Consumer

10. A power generating station transmits 100 MW of power at 132 kV to a main substation. If the resistance of the transmission line is 10 ohms, what is the percentage power loss during transmission?

a) 4.32\%

b) 5.74\%

c) 7.12\%

d) 8.45\%

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Category: Power Distribution to a House

11. (A) The earth wire in a house's power distribution system is connected to the neutral wire at the sub-station.
(R) This connection ensures that the earth wire provides a safe path for leakage current, preventing electric shocks.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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Category: CIRCUITS WITH DUAL CONTROL SWITCHES (STAIRCASE WIRING)

12. Why is a dual control switch considered a double pole switch of special kind?

a) It has two separate knobs for operation.

b) It can only be used in staircase wiring.

c) It allows control of an appliance from two different locations.

d) It requires higher voltage to operate.

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Category: TRANSMISSION OF POWER FROM THE GENERATING STATION TO THE CONSUMER

13. (A) Stepping up the transmission voltage from 11 kV to 132 kV reduces the energy loss in transmission lines significantly.
(R) The power loss in transmission lines is directly proportional to the square of the current, as given by $P_{\text{loss}} = I^2 R$.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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Category: SAFETY PRECAUTIONS WHILE USING THE ELECTRICITY

14. For an appliance with a motor that draws higher current during startup, what should be the rating of its fuse?

a) Equal to the running current

b) Lower than the starting current

c) Slightly more than the starting current

d) Much higher than the running current

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Category: Choosing the Correct Fuse

15. Why should a fuse never be replaced with an ordinary copper or aluminium wire?

a) It increases the resistance of the circuit

b) It reduces the voltage drop

c) It cannot melt and break the circuit during overcurrent

d) It makes the circuit more efficient

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Category: Circuit Diagrams for Connecting Appliances

16. Why are household electrical appliances connected in parallel to the mains supply?

a) Each appliance gets a lower voltage than required

b) All appliances must be switched on or off together

c) Each appliance operates independently at rated voltage

d) The total resistance of the circuit decreases

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Category: The Role of Fuse in Household Circuits

17. (A) A fuse wire is made of an alloy of lead and tin.
(R) The alloy of lead and tin has a low melting point and high resistance.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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Category: Transmission of Power from the Power Station to the Consumer

18. At what voltage is electric power typically generated at the power station?

a) 220 V

b) 11 kV

c) 33 kV

d) 132 kV

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Category: Connection of all appliances (bulb, fan, socket, etc.) with the mains

19. Why are household appliances connected in parallel rather than in series?

a) Each appliance gets divided voltage and operates independently.

b) Each appliance gets full voltage but cannot operate independently.

c) Each appliance gets full voltage and operates independently.

d) Each appliance gets divided voltage but operates simultaneously.

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Category: CIRCUITS WITH DUAL CONTROL SWITCHES (STAIRCASE WIRING)

20. (A) In a staircase wiring setup with dual control switches, the bulb can be turned on or off from either switch regardless of the current state of the other switch.
(R) Dual control switches work by altering the connections between terminals 'a', 'b', and 'c' to complete or break the circuit.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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Category: Connection of all appliances (bulb, fan, socket, etc.) with the mains

21. (A) All electrical appliances in a household are connected in parallel to the mains supply.
(R) This ensures each appliance operates at its rated voltage and can function independently.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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Category: Neutral Wire

22. An electrician is wiring a new three-pin plug for a geyser. Which pin should the blue wire be connected to, and why?

a) Left pin, because it provides grounding.

b) Right pin (N), as it is the neutral connection.

c) Middle pin, as it carries the live current.

d) Any pin, as the color does not matter.

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Category: Power Distribution to a House

23. What is the purpose of the company fuse (\$50 A\$ rating) connected in the live wire at the pole?

a) To reduce voltage fluctuations

b) To measure the electricity consumption

c) To protect the system from excessive current

d) To increase the power supply efficiency

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Category: Live Wire

24. Which statement correctly describes the function of the live wire in an electrical circuit?

a) It returns unused current back to the source.

b) It prevents electrical shocks by grounding the appliance.

c) It provides a path for excess current to escape.

d) It carries current from the supply to the appliance.

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Category: Live Wire

25. Which of the following correctly identifies the color-coding and purpose of the live wire in household wiring?

a) Red or brown, carries current from the appliance to the power source

b) Black or light blue, carries current from the power source to the appliance

c) Green, provides a safety path for leakage current

d) Red or brown, carries current from the power source to the appliance

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Category: Choosing the Correct Fuse

26. (A) A fuse with a current rating higher than the appliance's requirement should never be used as it compromises safety.
(R) The fuse must be connected in the live wire to prevent the appliance from remaining at high potential after the fuse blows.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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Category: Dual Control Switches and Staircase Wiring

27. Why must a dual control switch never be touched with wet hands when installing or operating it?

a) It may cause the switch to malfunction due to moisture

b) Water can cause corrosion in the switch contacts over time

c) Wet hands increase the risk of slipping while operating the switch

d) Water conducts electricity, leading to potential electric shock

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Category: Practical Questions and Problems

28. According to standard electrical wiring color codes, what does a green-colored insulation on a wire indicate?

a) Live wire carrying current

b) Neutral wire completing the circuit

c) Earth wire for safety grounding

d) Wire with no specific function

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Category: Connection of all appliances (bulb, fan, socket, etc.) with the mains

29. What does the green insulation on a wire indicate in house wiring?

a) It indicates the live wire.

b) It indicates the neutral wire.

c) It indicates the earth wire.

d) It indicates a high-voltage wire.

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Category: Household Wiring (Ring System)

30. Why is it important that the total current drawn by all appliances on a ring circuit must not exceed the main fuse rating (30 A)?

a) To reduce electricity consumption

b) To ensure compatibility with all plug sizes

c) To prevent overheating and potential fire hazards

d) To increase the efficiency of electrical appliances

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Category: Three-Pin Plug and Socket

31. What is the purpose of the earth pin being longer and thicker in a three-pin plug?

a) To make the plug look different from others

b) To provide better grip while inserting the plug

c) To ensure the earth connection is made first and prevent incorrect insertion

d) To reduce the resistance of the earthing wire

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Category: Three-Pin Plug and Socket

32. Why is the earth pin in a three-pin plug made thicker and longer than the live and neutral pins?

a) To make the plug easier to insert into the socket

b) To ensure the earth connection is made first for safety and prevent wrong insertion

c) To reduce manufacturing costs of the plug

d) To allow higher current flow through the earth pin

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Category: Dual Control Switches and Staircase Wiring

33. Why shouldn't dual control switches be operated with wet hands?

a) It causes corrosion of switch contacts

b) Water makes switches harder to operate

c) It provides conducting path for current to human body

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Category: Neutral Wire

34. In a lighting circuit, if the neutral wire is disconnected but the live wire is still connected, what happens when the switch is turned on?

a) The bulb glows dimly due to reduced current flow.

b) The bulb glows normally as the live wire carries current.

c) The bulb does not glow because the circuit is incomplete.

d) The bulb flickers intermittently due to unstable current.

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Category: Choosing the Correct Fuse

35. (A) A 15 A fuse is recommended for an electric motor operating at 220 V with a power rating of 3 kW.
(R) The current rating of the fuse is calculated using the formula $I = \frac{P}{V}$.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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Category: Fuse and Switch Locations

36. Where should a fuse be connected in an electrical circuit?

a) In both live and neutral wires

b) Only in the neutral wire

c) Only in the live wire

d) Across the appliance terminals

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Category: Step-Up and Step-Down Transformers

37. What is the primary purpose of a step-up transformer in power transmission?

a) To decrease voltage for domestic use

b) To increase current for efficient transmission

c) To change AC to DC for better transmission

d) To increase voltage for efficient long-distance transmission

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Category: Proper Insulation

38. A dual control switch is installed in a staircase to control a light from two different locations. How does switching off the light from one switch affect the state of the other switch?

a) The other switch becomes non-functional

b) The other switch must be reset manually

c) Both switches must be turned off simultaneously

d) The other switch can still turn the light on/off

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Category: Household Wiring (Ring System)

39. What happens when appliances are connected in parallel in a household wiring system?

a) The total resistance decreases, increasing the current in the circuit

b) All appliances share the same current and operate at reduced voltage

c) Each appliance gets the same voltage and operates independently

d) The circuit becomes more resistant to electrical faults

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Category: Choosing the Correct Fuse

40. (A) Copper is a suitable material for fuse wire due to its high melting point.
(R) A fuse wire should have a low melting point to break the circuit during overcurrent.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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Category: Neutral Wire

41. In a three-pin plug, where is the neutral wire connected?

a) Left pin

b) Right pin

c) Top pin

d) Bottom pin

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Category: Transmission of Power from the Power Station to the Consumer

42. (A) Power is transmitted at high voltages to reduce energy loss in transmission lines.
(R) According to the relation $P = VI$, for a given power, higher voltage reduces current, minimizing energy loss as heat ($I^2Rt$).

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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Category: Current Rating

43. (A) The current rating of a fuse must always be higher than the maximum current drawn by the appliance it protects.
(R) A fuse with a lower current rating than the appliance's maximum current will blow under normal operation, causing unnecessary circuit interruptions.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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Category: TRANSMISSION OF POWER FROM THE GENERATING STATION TO THE CONSUMER

44. A step-down transformer at an intermediate substation steps down the voltage from $33 \text{ kV}$ to $11 \text{ kV}$. If the transformer is 95\% efficient and the input power is $200 \text{ MW}$, what is the current supplied to the light industries assuming no additional losses?

a) 15.45 kA

b) 17.27 kA

c) 18.18 kA

d) 16.36 kA

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Category: COLOUR CODING OF WIRES IN A CABLE

45. An electrician finds that the metallic case of a geyser is giving a mild shock. Which wire's improper connection is most likely causing this issue?

a) Live wire

b) Neutral wire

c) Earth wire

d) Fuse wire

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Category: Three-Pin Plug and Socket

46. What should be ensured while inserting a plug into a socket to avoid sparking and burning?

a) The hands must be wet

b) The plug pins should fit loosely

c) The plug pins should fit tightly

d) The earth pin should be removed

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Category: Advantages of connecting the appliances in parallel

47. (A) When appliances are connected in parallel, the total resistance of the circuit decreases, leading to higher current flow.
(R) In a parallel connection, each appliance operates at its rated voltage due to the shared voltage across all branches.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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Category: Main Fuse and Meter

48. Which of the following materials is unsuitable for use as a fuse wire?

a) Tin-lead alloy

b) Copper

c) Silver

d) Zinc

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Category: Reason for connecting the fuse in the live wire

49. Why is a fuse always connected in the live wire rather than the neutral wire?

a) To reduce the cost of wiring

b) To ensure the circuit breaks completely and prevents shock hazard

c) Because the neutral wire is thicker than the live wire

d) To increase the efficiency of the appliance

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Category: Reason for connecting the fuse in the live wire

50. In a properly wired household circuit with the fuse in the live wire, what happens first when a short circuit occurs?

a) The appliance burns out before the fuse blows

b) The neutral wire starts overheating

c) The fuse melts and breaks the circuit

d) The voltage drops to zero gradually

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Category: Proper Insulation

51. (A) High tension wires are made by twisting together multiple thin wires insulated from each other.
(R) Twisting multiple thin wires increases the surface area, allowing better heat dissipation compared to a single thick wire.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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Category: Advantages of connecting the appliances in parallel

52. In a household electrical circuit, why is it advantageous to connect appliances like a refrigerator and a microwave in parallel rather than in series?

a) Appliances share the same current, reducing power consumption

b) Each appliance works at its rated voltage and operates independently regardless of other appliances

c) The total resistance increases, making the circuit safer

d) It reduces the number of wires needed for installation

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Category: COLOUR CODING OF WIRES IN A CABLE

53. What is the colour code for the live wire in a three-core flexible cable?

a) Red

b) Black

c) Green

d) Blue

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Category: Circuit Diagrams for Connecting Appliances

54. (A) In a ring system of wiring, each appliance can draw current through two separate paths.
(R) This ensures that the wire required for the main ring has a lower current-carrying capacity than a direct connection to the mains.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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Category: Choosing the Correct Fuse

55. A circuit uses three appliances: one 100 W bulb, one 1500 W heater, and one 1200 W air conditioner, all operating at 220 V. What is the total current drawn from the mains?

a) 10 A

b) 11 A

c) 13 A

d) 15 A

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Category: Transmission of Power from the Power Station to the Consumer

56. Why is electric power transmitted at high voltages over long distances?

a) To increase energy consumption

b) To decrease the resistance of transmission lines

c) To minimize energy loss as heat

d) To reduce the need for transformers

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Category: Transmission of Power from the Power Station to the Consumer

57. If the voltage at an intermediate substation is stepped down from 33 kV to 11 kV and the power delivered is 50 MW, what is the approximate ratio of the currents before and after the step-down transformer if the transformer is ideal?

a) 1:1

b) 1:2

c) 1:3

d) 3:1

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Category: COLOUR CODING OF WIRES IN A CABLE

58. (A) The earth pin in a three-pin plug is made longer and thicker than the other two pins.
(R) This ensures that the earth connection is made first and prevents incorrect insertion into live or neutral holes.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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Category: Neutral Wire

59. Why is the neutral wire essential in an electrical circuit?

a) It provides power to the appliance

b) It acts as a safety measure to prevent electric shocks

c) It completes the circuit by returning current to the source

d) It carries excess voltage away from the appliance

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Category: Earth Wire

60. Why is the earth pin in a three-pin plug thicker and longer than the live and neutral pins?

a) To carry higher current than the live and neutral wires

b) To prevent reverse polarity

c) To make the plug more durable

d) To ensure the earth connection is made first for safety

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Category: Household Wiring (Ring System)

61. (A) In the ring system of household wiring, each appliance is connected in parallel to the mains.
(R) Parallel connection ensures that a fault in one appliance does not affect the operation of other appliances.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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Category: Earthing (Grounding)

62. Why is the earth pin in a three-pin plug made thicker and longer than the live and neutral pins?

a) To make the plug durable

b) To reduce manufacturing costs

c) To prevent insertion into live/neutral holes and ensure first contact

d) For aesthetic reasons

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Category: Safety Precautions in Household Circuits

63. What is the main advantage of using a Miniature Circuit Breaker (MCB) over a traditional fuse?

a) It is cheaper than a fuse

b) It can be reused after a fault is repaired

c) It has a slower response time than a fuse

d) It does not require any maintenance

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Category: The Role of Fuse in Household Circuits

64. What is the primary safety risk if a fuse is connected in the neutral wire instead of the live wire in a household circuit?

a) The appliance may overheat without tripping the fuse

b) The fuse will blow more frequently

c) The appliance remains connected to the live wire when the fuse blows, risking electric shock

d) The circuit breaker will trip unnecessarily

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Category: Parallel Circuits:

65. (A) In a parallel circuit, if one appliance stops working, other appliances continue to function.
(R) In a parallel connection, each appliance receives the full supply voltage independently.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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Category: Earthing (Grounding)

66. What is the primary safety benefit of earthing the metallic case of an electrical appliance?

a) Reduces power consumption

b) Prevents overheating of wires

c) Avoids electric shock to the user

d) Increases the appliance's efficiency

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Category: Household Wiring (Ring System)

67. In a household ring system wiring, if three appliances (a lamp rated 60 W, a fan rated 80 W, and a socket supplying a device rated 100 W) are connected in parallel to the same ring circuit, what is the total current drawn from the mains when all appliances are operating at 220 V?

a) 0.5 A

b) 1.09 A

c) 1.5 A

d) 2.0 A

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Category: Neutral Wire

68. Why must the switch be connected in the live wire and not the neutral wire?

a) To reduce power consumption

b) To ensure the appliance remains at high potential when switched off

c) To prevent electric shock by disconnecting the high voltage supply when switched off

d) To increase the lifespan of the switch

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Category: Dual Control Switches and Staircase Wiring

69. Where is a dual control switch commonly used?

a) At a single location only

b) In staircases and long corridors

c) Only for industrial purposes

d) For high-voltage applications

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Category: Working Mechanism

70. A dual control switch installation isn't working - bulb remains off regardless of switch positions. Testing reveals continuity between terminals 'b' and 'c' of BOTH switches in all knob positions. What is the most likely fault?

a) Both switches have broken knobs

b) Bulb filament has burned out \input{The 'a' terminals are shorted together}

c) Neutral wire is disconnected

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Category: COLOUR CODING OF WIRES IN A CABLE

71. In a household wiring system, where must the switch and fuse be connected for safe operation?

a) Neutral wire

b) Earth wire

c) Live wire

d) Either neutral or live wire

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Category: Parallel Circuits:

72. In a car's rear light system, two bulbs are connected in parallel to a 12 V battery. If one bulb burns out, what happens to the current through the other bulb?

a) It becomes zero.

b) It decreases.

c) It increases.

d) It remains the same.

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Category: Appliance Earthing

73. In a three-pin plug, why is the earth pin longer and thicker than the other two pins?

a) To make it easier to manufacture

b) To distinguish it visually from the other pins

c) To ensure strong mechanical connection

d) For safety reasons: to establish earth connection first and prevent wrong insertion

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Category: Safety Precautions in Household Circuits

74. (A) High tension wires are made by twisting together multiple thin insulated wires to increase their resistance and reduce heat dissipation.
(R) A single thick wire of low resistance would have less surface area, making it less efficient at radiating heat compared to multiple thin wires.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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Category: CIRCUITS WITH DUAL CONTROL SWITCHES (STAIRCASE WIRING)

75. (A) In a staircase wiring setup with dual control switches, toggling either switch $S_1$ or $S_2$ changes the state of the bulb (on/off).
(R) Dual control switches work by altering the connection between terminals 'a', 'b', and 'c' to either complete or break the circuit, allowing control from two different locations.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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Category: Earthing (Grounding)

76. Why must the paint be removed from the connection point when earthing an appliance's metallic case?

a) To make the appliance look neat

b) To avoid corrosion of the metallic case

c) To ensure proper electrical contact

d) To reduce the weight of the appliance

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Category: Transmission of Power from the Power Station to the Consumer

77. In a power transmission system, stepping up the voltage from $11 \text{kV}$ to $132 \text{kV}$ reduces the current by a factor of:

a) 10

b) 11

c) 12

d) 13

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Category: Earth Wire

78. What is the primary purpose of an earth wire in an electrical appliance?

a) To complete the circuit and allow normal operation of the appliance

b) To provide a return path for the neutral current

c) To supply additional power to the appliance during high load

d) To prevent fire hazards by diverting fault current to the ground

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Category: Dual Control Switch

79. If a bulb is initially off in a staircase setup with dual control switches S1 and S2, which of the following actions will turn it on?

a) Operating only S1 by shifting its knob to the left

b) Operating only S2 by shifting its knob to the up position

c) Operating both S1 and S2 simultaneously

d) Operating either S1 by shifting its knob to the right or S2 by shifting its knob to the left

80 / 491

Category: Household Wiring (Ring System)

80. (A) In the ring system of household wiring, each appliance has a separate fuse connected in series with the live wire.

(R) This ensures that if one appliance's fuse blows due to a fault, it does not affect the operation of other appliances connected in the same ring.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

81 / 491

Category: Avoid Wet Hands:

81. (A) Touching an electrical switch with wet hands can result in a fatal electric shock.
(R) Water forms a conducting layer between the hand and the live wire, allowing current to pass through the body.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

82 / 491

Category: FUSE

82. Which of the following materials is most suitable for use as a fuse wire and why?

a) Copper, due to its high conductivity

b) Aluminum, because it is lightweight

c) Lead-tin alloy, due to low melting point and high resistance

d) Silver, because of its excellent thermal conductivity

83 / 491

Category: Fuse and Switch Locations

83. (A) A fuse should always be connected in the live wire.
(R) Connecting a fuse in the neutral wire can leave the appliance at high potential even after the fuse blows.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

84 / 491

Category: Household Wiring (Ring System)

84. In the ring system of household wiring, why is a separate fuse provided for each appliance?

a) To increase the current capacity of the main ring circuit

b) To allow the use of thicker wires for all appliances

c) To reduce the cost of the wiring system

d) To isolate faults in individual appliances without affecting others

85 / 491

Category: Power Distribution to a House

85. In a residential power distribution system using the ring system of wiring, if a fault occurs in one appliance, why does it not affect the operation of other appliances connected to the same ring?

a) The fault causes all appliances to shut down simultaneously.

b) The main fuse blows, cutting power to the entire house.

c) Each appliance has an independent path through its own fuse.

d) The earth wire diverts the fault current to the ground.

86 / 491

Category: Power Generation

86. (A) Electric power from generating stations is transmitted at higher voltages to minimize energy loss.
(R) Power loss in transmission lines is given by $P_{loss} = I^2 R$, where reducing current decreases losses.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

87 / 491

Category: Safety Precautions in Household Circuits

87. (A) The earth wire in a three-pin plug is connected to the metallic case of an appliance.
(R) This prevents electric shock by diverting current to the ground if the live wire touches the metallic case.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

88 / 491

Category: Connection of all appliances (bulb, fan, socket, etc.) with the mains

88. If two bulbs rated 220 V, 100 W and 220 V, 60 W are incorrectly connected in series to a 440 V supply, which bulb will glow brighter and why?

a) The 100 W bulb glows brighter due to higher power rating

b) Both bulbs glow with equal brightness

c) The 60 W bulb glows brighter due to higher resistance

d) Neither bulb glows as the voltage exceeds their ratings

89 / 491

Category: FUSE

89. (A) A fuse is connected in the live wire to protect electrical appliances.
(R) The fuse melts and breaks the circuit when excessive current flows.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

90 / 491

Category: Three-Pin Plug and Socket

90. Which colour is used for the live wire in a three-core flexible cable?

a) Green

b) Black or light blue

c) Red or brown

d) Yellow

91 / 491

Category: Function of Fuse

91. A fuse wire made of an alloy of lead and tin has a radius of 0.3 mm and a current rating of 3 A. If the same material is used for another fuse wire with a current rating of 6 A, what should be its radius? Assume all other parameters remain constant.

a) 0.15 mm

b) 0.30 mm

c) 0.48 mm

d) 0.60 mm

92 / 491

Category: Disadvantages of connecting the appliances in series

92. Why can't appliances be operated independently in a series connection?

a) Appliances receive different voltages.

b) The circuit overheats.

c) The current path breaks if one appliance is turned off.

d) The power supply voltage fluctuates.

93 / 491

Category: Earthing (Grounding)

93. Why is the earth pin in a three-pin plug thicker and longer than the other pins?

a) To distinguish it visually from other pins

b) To make the plug harder to insert incorrectly

c) To ensure the earth connection is established first and broken last

d) To reduce manufacturing costs

94 / 491

Category: The Role of Fuse in Household Circuits

94. Why is an alloy of lead and tin commonly used as a fuse wire instead of copper or aluminum?

a) Copper and aluminum have lower resistance than lead-tin alloy

b) Lead-tin alloy has a high melting point compared to copper

c) Lead-tin alloy is cheaper and more readily available

d) Lead-tin alloy has a low melting point and high specific resistance

95 / 491

Category: HOUSE WIRING (RING SYSTEM)

95. (A) In a ring system of house wiring, the current from mains can reach an appliance through two separate paths.
(R) This reduces the cost of wiring as the main ring wire can have a lower current carrying capacity compared to direct connection.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

96 / 491

Category: Neutral Wire

96. What is the color of the neutral wire in household electrical wiring?

a) Red

b) Green

c) Yellow

d) Blue

97 / 491

Category: Dual Control Switch

97. (A) A dual control switch allows controlling an appliance from two different locations.
(R) It works by changing the connections between terminals to either complete or break the circuit.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

98 / 491

Category: Practical Questions and Problems

98. (A) The metallic case of an electric appliance is connected to the earth wire for safety purposes.
(R) Earthing prevents electric shock by providing a low-resistance path for leakage current.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

99 / 491

Category: Parallel Circuits:

99. A fuse with a rating of 5 A is connected in series with an appliance drawing 4.5 A. If the resistance of the fuse wire is $0.02 \,\Omega$, how much heat energy is produced in the fuse in 10 seconds?

a) 2.025 J

b) 4.05 J

c) 8.1 J

d) 0.405 J

100 / 491

Category: Safety through Earthing

100. (A) The earth pin in a three-pin plug is made longer and thicker than the other two pins.
(R) This ensures that the earth connection is made first when inserting the plug, enhancing user safety.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

101 / 491

Category: Advantages of connecting the appliances in parallel

101. Why is a fuse placed in the live wire before an appliance in household wiring?

a) To increase the current flow to the appliance.

b) To reduce the voltage across the appliance.

c) To protect the appliance from excessive current.

d) To allow the appliance to work even during a short circuit.

102 / 491

Category: Safety through Earthing

102. Why is the metallic case of an appliance earthed?

a) To increase the efficiency of the appliance

b) To ensure the appliance works at higher voltages

c) To prevent rusting of the metallic case

d) To protect users from electric shocks by diverting fault current to the ground

103 / 491

Category: SAFETY PRECAUTIONS WHILE USING THE ELECTRICITY

103. Which of the following precautions helps prevent electric shock when using an appliance?

a) Checking the insulation of wires regularly

b) Operating the appliance with wet hands

c) Using a fuse of lower rating than required

d) Not earthing the metallic case of the appliance

104 / 491

Category: SAFETY PRECAUTIONS WHILE USING THE ELECTRICITY

104. What is the main advantage of using a Miniature Circuit Breaker (MCB) over a traditional fuse?

a) It does not require replacement after tripping

b) It has a delayed response to faults

c) It needs manual rewiring after tripping

d) It is cheaper than a traditional fuse

105 / 491

Category: Fuse and Switch Locations

105. Which type of switch is used to disconnect both live and neutral wires simultaneously at the distribution board?

a) Single-pole switch

b) Double-pole switch

c) Triple-pole switch

d) Push-button switch

106 / 491

Category: CIRCUITS WITH DUAL CONTROL SWITCHES (STAIRCASE WIRING)

106. Consider a staircase wiring setup with two dual control switches $S_1$ and $S_2$ controlling a bulb. If the bulb is initially off and the connection in $S_1$ is 'ba' while in $S_2$ it is 'bc', which of the following actions will turn the bulb on?

a) Changing $S_1$ from 'ba' to 'bc'

b) Changing $S_2$ from 'bc' to 'ba' \button Leaving both switches unchanged \button Changing $S_1$ from 'ba' to 'ab'

107 / 491

Category: Practical Questions and Problems

107. What is the purpose of the earth pin in a three-pin plug?

a) To increase the stability of the plug when inserted into the socket

b) To provide a return path for the current to complete the circuit

c) To connect the live and neutral wires internally

d) To divert leakage current safely to the ground

108 / 491

Category: Advantages of connecting the appliances in parallel

108. Why are appliances generally not connected in series?

a) They receive higher voltage than rated

b) The circuit resistance decreases with more appliances

c) All appliances must operate simultaneously

d) Each appliance can be controlled individually

109 / 491

Category: Step-Up and Step-Down Transformers

109. A power station generates electricity at $11 \text{ kV}$. To transmit this over a long distance with minimal power loss, it is stepped up to $132 \text{ kV}$ using a transformer. If the resistance of the transmission line is $10 \Omega$, what is the percentage reduction in power loss after stepping up the voltage compared to transmitting directly at $11 \text{ kV}$ for the same power delivered?

a) 90\%

b) 96\%

c) 99.31\%

d) 92.5\%

110 / 491

Category: Advantages of connecting the appliances in parallel

110. (A) When appliances are connected in parallel, each appliance operates independently without affecting others.
(R) In a parallel connection, the voltage across each appliance remains equal to the supply voltage.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

111 / 491

Category: Neutral Wire

111. What is the primary function of the neutral wire in an electrical circuit?

a) To provide a safety path for fault currents

b) To complete the circuit by providing a return path for current

c) To act as a backup live wire

d) To ground the appliance

112 / 491

Category: Working Mechanism

112. A device converts electrical energy into mechanical energy with an efficiency of 80\%. If the input power is 500 W, what is the output mechanical power?

a) 300 W

b) 400 W

c) 450 W

d) 600 W

113 / 491

Category: Step-Up and Step-Down Transformers

113. A step-down transformer is used to reduce the voltage from $33 \text{ kV}$ to $11 \text{ kV}$ for local distribution. If the primary coil has 3000 turns, how many turns should the secondary coil have?

a) 500 turns

b) 1000 turns

c) 1500 turns

d) 2000 turns

114 / 491

Category: The Role of Fuse in Household Circuits

114. Where should the fuse be connected in a household circuit for safety?

a) In the neutral wire after the appliance.

b) In both live and neutral wires.

c) In the live wire before the appliance.

d) In the earth wire.

115 / 491

Category: Step-Up and Step-Down Transformers

115. (A) Step-up transformers are used at power generating stations to increase the voltage for long-distance transmission.
(R) Higher voltage reduces the current in transmission lines, minimizing energy loss as heat according to $P_{\text{loss}} = I^2 R t$.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

116 / 491

Category: Fuse and Switch Locations

116. A geyser has a power rating of 3000 W and operates at 220 V. What should be the current rating of the fuse used in its circuit?

a) 10 A

b) 5 A

c) 15 A

d) 20 A

117 / 491

Category: Advantages of connecting the appliances in parallel

117. What is one major advantage of connecting appliances in parallel?

a) Each appliance operates at a reduced voltage

b) All appliances must be switched on together

c) Appliances share the same current

d) Each appliance works independently and receives full voltage

118 / 491

Category: Circuit Diagrams for Connecting Appliances

118. In household wiring, why is the switch always connected to the live wire and not the neutral wire?

a) It reduces power consumption when the switch is off.

b) It helps in balancing the current flow in the circuit.

c) It ensures the appliance remains safe for repair when switched off.

d) It increases the lifespan of the appliance.

119 / 491

Category: Neutral Wire

119. (A) Connecting a switch in the neutral wire of an appliance ensures safety when the switch is turned off.
(R) The neutral wire is at zero potential relative to earth, so it does not pose any risk even if current flows through it.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

120 / 491

Category: Choosing the Correct Fuse

120. An electric heater has a power rating of 2 kW and operates at a mains voltage of 220 V. What is the current rating of the fuse required for this heater?

a) 5 A

b) 7.5 A

c) 10 A

d) 15 A

121 / 491

Category: Transmission of Power from the Power Station to the Consumer

121. A power generating station produces electricity at $11 \text{kV}$. At the grid sub-station, this voltage is stepped up to $132 \text{kV}$ for transmission. If the current in the transmission line is $500 \text{A}$, what is the approximate power being transmitted?

a) 6.6 MW

b) 660 MW

c) 66 MW

d) 132 MW

122 / 491

Category: Three-Pin Plug and Socket

122. What is the colour code for the insulation on the live wire in a three-core flexible cable?

a) Green

b) Black (or light blue)

c) Red (or brown)

d) Yellow

123 / 491

Category: Three-Pin Plug and Socket

123. In a three-pin socket, which hole is connected to the live wire?

a) Upper bigger hole

b) Hole on the left

c) Hole on the right

d) None of the above

124 / 491

Category: Practical Questions and Problems

124. In which wire should the fuse be placed in a power circuit for safety reasons?

a) Neutral wire

b) Earth wire

c) Both live and neutral wires

d) Live wire

125 / 491

Category: FUSE

125. A fuse wire has a resistance of 0.5 $\Omega$ and is designed to melt when the power dissipated in it reaches 50 W. What is the current rating of this fuse?

a) 5 A

b) 10 A

c) 15 A

d) 20 A

126 / 491

Category: Three-Pin Plug and Socket

126. (A) The earth pin in a three-pin plug is made thicker and longer than the live and neutral pins.
(R) This ensures the earth connection is established first and prevents accidental insertion into live or neutral holes.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

127 / 491

Category: Safety Precautions in Household Circuits

127. A water pump rated at 2.2 kW, 220 V has a motor that draws 12 A when starting and settles to 8 A during normal operation. What should be the minimum current rating of the fuse for this appliance?

a) 8 A

b) 10 A

c) 12 A

d) 13 A

128 / 491

Category: Dual Control Switches and Staircase Wiring

128. A dual control switch is used in staircase wiring with switches $S_1$ and $S_2$ controlling a bulb. Initially, the bulb is off. If switch $S_1$ is operated to change its connection from 'ba' to 'bc', what will happen if $S_2$ is then operated to change its connection from 'bc' to 'ba'?

a) The bulb remains on as the circuit remains complete

b) The bulb turns off as the circuit breaks

c) The bulb flickers due to incomplete connection

d) The bulb's state cannot be determined without knowing the initial positions of both switches

129 / 491

Category: Earthing (Grounding)

129. What is the primary purpose of local earthing in a household electrical system?

a) To increase the efficiency of electrical appliances

b) To reduce electricity consumption

c) To provide a safe path for fault currents to the ground

d) To stabilize voltage fluctuations in the circuit

130 / 491

Category: Earthing (Grounding)

130. Why is the earth pin in a three-pin plug made thicker and longer than the live and neutral pins?

a) To distinguish it visually from the other pins

b) To reduce the cost of manufacturing

c) To ensure the earth connection is established first for safety

d) To allow higher current flow through the earth wire

131 / 491

Category: Fuse and Switch Locations

131. Why is it unsafe to connect a fuse in the neutral wire?

a) It prevents overloading of the circuit

b) It ensures the appliance remains safe during voltage fluctuations

c) The appliance stays connected to the live wire after the fuse blows, risking electric shock

d) It reduces the efficiency of the appliance

132 / 491

Category: Reason for connecting the fuse in the live wire

132. A 2000W geyser operates at 230V mains supply. What should be the minimum current rating of the fuse used for this appliance?

a) 5A

b) 8.7A

c) 10A

d) 15A

133 / 491

Category: Safety Precautions in Household Circuits

133. For an appliance like a water pump, how should the fuse rating be determined?

a) Equal to the running current of the appliance

b) Slightly less than the starting current of the appliance

c) Slightly more than the starting current of the appliance

d) Twice the running current of the appliance

134 / 491

Category: Function of Fuse

134. Why is a thicker fuse wire used for heavy current consuming appliances like air conditioners?

a) To reduce resistance in the circuit

b) To allow more current without melting under normal conditions

c) To decrease the cost of the fuse

d) To improve the efficiency of the appliance

135 / 491

Category: Safety through Earthing

135. What happens if the live wire accidentally comes in contact with the metallic case of an earthed appliance?

a) The appliance continues to function normally without any issue

b) The current flows back through the neutral wire, causing overheating

c) The fuse blows, and the appliance is disconnected from the power supply

d) The metallic case becomes positively charged

136 / 491

Category: Power Distribution to a House

136. (A) The company fuse in a power distribution system is placed before the kWh meter to protect the entire household circuit from overloading.
(R) The company fuse has a high rating (\$50 A\$) because it needs to handle the total current drawn by all appliances in the house without blowing under normal conditions.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

137 / 491

Category: Energy Consumption

137. (A) When two identical bulbs rated '220 V, 60 W' are connected in series to a 220 V mains, the total power consumed is 30 W.
(R) In a series connection, the voltage across each bulb becomes half of the supply voltage.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

138 / 491

Category: Household Wiring (Ring System)

138. (A) In the ring system of household wiring, the fuse rating for the main distribution box is typically 30 A because the total current drawn by all appliances in the ring should not exceed this limit.
(R) The ring system allows multiple paths for current to reach an appliance, reducing the effective resistance and thus preventing excessive current flow.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

139 / 491

Category: SAFETY PRECAUTIONS WHILE USING THE ELECTRICITY

139. A water pump rated at 1.5 kW and 220 V draws a starting current of 10.4 A and a running current of 6.8 A. What should be the minimum current rating of the fuse used with this pump to ensure safety?

a) 5 A

b) 7 A

c) 10.5 A

d) 15 A

140 / 491

Category: Connection of all appliances (bulb, fan, socket, etc.) with the mains

140. A household circuit has three appliances connected in parallel: a bulb rated 220 V, 100 W; a fan rated 220 V, 60 W; and a socket rated 220 V, 2000 W. If the total current drawn from the mains is 10 A, what happens when the socket is switched off?

a) The total current becomes zero

b) The bulb and fan stop working

c) The total current reduces to approximately 0.72 A, while the bulb and fan continue working normally

d) The voltage across the bulb and fan increases

141 / 491

Category: Energy Consumption

141. An electric bulb rated '220 V, 60 W' is connected to a 220 V supply. If another identical bulb is connected in series with it and the system is connected across the same supply, what will be the total power consumed by both bulbs?

a) 30 W

b) 60 W

c) 120 W

d) 180 W

142 / 491

Category: Transmission of Power from the Power Station to the Consumer

142. A city sub-station receives power at 11 kV and steps it down to 220 V for domestic use. If the total power delivered is 20 MW and the resistance of the distribution line is 2 ohms, what is the efficiency of the transmission system (ignore losses in transformers)?

a) 65.45\%

b) 70.22\%

c) 75.13\%

d) 80.05\%

143 / 491

Category: Current Rating

143. A circuit is protected by a 10 A MCB at 220 V. If a new appliance consuming 2.5 kW is added to this circuit, what will happen?

a) The MCB will allow the appliance to operate normally

b) The MCB will trip after some time due to overheating

c) The MCB will trip immediately

d) The appliance will operate at reduced power

144 / 491

Category: Earthing (Grounding)

144. (A) Local earthing is done near the kWh meter to ensure safety in case of excessive current flow.
(R) The copper plate in local earthing is surrounded by a mixture of charcoal and salt to improve conductivity.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

145 / 491

Category: Avoid Wet Hands:

145. (A) Operating electrical appliances with wet hands can cause an electric shock.
(R) Water acts as a conductor and provides a path for electric current to flow through the body.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

146 / 491

Category: Power Distribution to a House

146. (A) The earth wire ensures safety by providing a path for fault currents to the ground.
(R) The earth wire is connected to the metal covering of appliances and the local sub-station to maintain them at zero potential.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

147 / 491

Category: TRANSMISSION OF POWER FROM THE GENERATING STATION TO THE CONSUMER

147. At which sub-station is the voltage first stepped up from 11 kV to 132 kV during the transmission of electric power?

a) City sub-station

b) Intermediate sub-station

c) Main sub-station

d) Grid sub-station

148 / 491

Category: Circuit Diagrams for Connecting Appliances

148. Why is the earth pin in a three-pin plug made longer and thicker compared to the live and neutral pins?

a) To reduce manufacturing costs.

b) To allow higher current flow through the earth connection.

c) To ensure proper earthing before live connection and prevent wrong insertion.

d) To make the plug more durable.

149 / 491

Category: SAFETY PRECAUTIONS WHILE USING THE ELECTRICITY

149. A household circuit has multiple appliances with a total power rating of 5 kW when used simultaneously at 220 V. The wiring used has a current carrying capacity of 25 A. To prevent overheating, which additional measure is most critical?

a) Replace the wiring with a thicker gauge

b) Install a fuse rated at 15 A

c) Use appliances one at a time

d) Install a fuse rated at 25 A

150 / 491

Category: Appliance Earthing

150. Why is the earth pin in a three-pin plug made thicker and longer than the other two pins?

a) To make it easily identifiable among the three pins

b) To prevent it from being inserted into the live or neutral socket holes and to ensure it connects first

c) To reduce the resistance of the earth connection

d) To increase the durability of the plug

151 / 491

Category: Working Mechanism

151. What does the term "working mechanism" generally refer to?

a) A type of financial investment

b) The way a system functions internally

c) A mathematical equation

d) A form of biological cell

152 / 491

Category: Function of Fuse

152. Which material is commonly used for making fuse wires due to its low melting point?

a) Copper

b) Aluminium

c) Alloy of lead and tin

d) Silver

153 / 491

Category: Appliance Earthing

153. In a standard three-pin plug, how are the pins arranged when viewed from the front?

a) Top: Neutral, Left: Live, Right: Earth.

b) Top: Earth, Left: Neutral, Right: Live.

c) Top: Earth, Left: Live, Right: Neutral.

d) Top: Live, Left: Neutral, Right: Earth.

154 / 491

Category: Three-Pin Plug and Socket

154. What is the primary reason for removing paint from the metallic body of an appliance before making an earth connection?

a) To improve the aesthetic appearance of the appliance

b) To reduce the weight of the appliance

c) To ensure proper electrical contact by removing the insulating paint layer

d) To comply with international safety standards

155 / 491

Category: Main Fuse and Meter

155. The current rating of a fuse can be determined using the relation:
$I = \frac{P}{V}$
where $P$ is power and $V$ is voltage. What happens if the current rating of the fuse is higher than required?

a) The fuse will blow off frequently

b) The fuse will not protect the circuit from overload

c) The appliance will receive less voltage

d) The circuit efficiency will improve

156 / 491

Category: Energy Consumption

156. (A) When two identical bulbs rated '220 V, 60 W' are connected in series to a 220 V supply, the total power consumed is 30 W.
(R) In series connection, the voltage across each bulb becomes half while the resistance remains the same.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

157 / 491

Category: Dual Control Switches and Staircase Wiring

157. (A) A dual control switch allows a bulb to be switched on or off from two different locations.
(R) The dual control switch uses two separate switches connected in a way that changing the connection at either switch completes or breaks the circuit.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

158 / 491

Category: Advantages of connecting the appliances in parallel

158. A 220V supply is used to power a 100W bulb and a 1500W heater connected in parallel. What happens to the voltage across each appliance when another 500W fan is added to the same parallel circuit?

a) Voltage across each appliance decreases proportionally

b) Voltage across the bulb drops to zero

c) Voltage across each appliance remains \$220 V\$

d) Only the heater's voltage increases to compensate for the fan

159 / 491

Category: Energy Consumption

159. A fuse wire has a length of 5 cm, radius of 1 mm, and is made of a material with specific resistance $\rho = 1.72 \times 10^{-8}$ $\Omega\cdot$m. If the fuse melts when the current exceeds 5 A, what is the heat produced per second in the fuse just before it melts?

a) 6.85 $\times$ 10$^{-3}$ W

b) 1.37 $\times$ 10$^{-3}$ W

c) 3.42 $\times$ 10$^{-2}$ W

d) 1.71 $\times$ 10$^{-4}$ W

160 / 491

Category: The Role of Fuse in Household Circuits

160. (A) A fuse wire is made of an alloy of lead and tin.
(R) The alloy of lead and tin has a low melting point and high specific resistance.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

161 / 491

Category: Safety Precautions in Household Circuits

161. (A) The metallic case of an electrical appliance should be connected to the earth wire.
(R) Earthing prevents electric shock by providing a low-resistance path for leakage current.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

162 / 491

Category: TRANSMISSION OF POWER FROM THE GENERATING STATION TO THE CONSUMER

162. What is the purpose of the step-up transformer at the grid sub-station?

a) To decrease the voltage for safe transmission

b) To increase the frequency of the current

c) To convert AC to DC

d) To increase the voltage for efficient transmission

163 / 491

Category: Advantages of connecting the appliances in parallel

163. What happens if two bulbs are connected in series instead of parallel?

a) Both bulbs glow at full brightness.

b) The total resistance of the circuit increases.

c) If one bulb fails, the other also stops glowing.

d) The voltage across each bulb doubles.

164 / 491

Category: COLOUR CODING OF WIRES IN A CABLE

164. In a correctly wired plug, which wire should be connected to the fuse?

a) Earth wire

b) Neutral wire

c) Live wire

d) Both live and neutral wires

165 / 491

Category: Reason for connecting the fuse in the live wire

165. When excessive current flows in a circuit, what is the first thing that should happen for safety?

a) The appliance should continue working

b) The neutral wire should heat up

c) The fuse in live wire should melt to break circuit

d) The voltage should increase

166 / 491

Category: Earth Wire

166. What is the purpose of surrounding the copper plate with charcoal and salt in local earthing?

a) To insulate the copper plate

b) To prevent rusting of the copper plate

c) To ensure good contact with the earth

d) To increase the voltage rating

167 / 491

Category: Earth Wire

167. Why is the earth pin in a three-pin plug made thicker and longer?

a) To make the plug look different

b) To ensure the earth connection is made first

c) To reduce resistance in the circuit

d) To increase voltage supply

168 / 491

Category: Types of Fuses

168. What happens when the current through a fuse wire exceeds its specified rating?

a) The fuse wire becomes thicker

b) The fuse wire melts and breaks the circuit

c) The fuse wire starts conducting more current

d) The fuse wire changes color but continues to function

169 / 491

Category: Fuse and Switch Locations

169. (A) A fuse connected in the neutral wire ensures safety by preventing excessive current flow to the appliance.
(R) Connecting a fuse in the neutral wire prevents the appliance from remaining at high potential when the fuse blows.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

170 / 491

Category: TRANSMISSION OF POWER FROM THE GENERATING STATION TO THE CONSUMER

170. At what voltage is electric power typically generated at the power generating station?

a) $220 \text{ V}$

b) $11 \text{ kV}$

c) $33 \text{ kV}$

d) $132 \text{ kV}$

171 / 491

Category: Safety Precautions in Household Circuits

171. Which of the following is NOT a valid precaution to avoid electric shock from an appliance?

a) Checking insulation of wires regularly

b) Touching the appliance with wet hands

c) Providing proper earthing to the metallic case

d) Installing a fuse in the live wire

172 / 491

Category: Earthing (Grounding)

172. What is the purpose of surrounding the copper plate with a mixture of charcoal and salt in local earthing?

a) To increase the aesthetic appearance of the earthing setup

b) To prevent rusting of the copper plate

c) To reduce the cost of the earthing system

d) To improve electrical conductivity between the plate and the earth

173 / 491

Category: CIRCUITS WITH DUAL CONTROL SWITCHES (STAIRCASE WIRING)

173. Why is a dual control switch referred to as a "double pole switch of special kind"?

a) It has two knobs for operation \button It can control two appliances simultaneously \button It interrupts both live and neutral lines \button It allows control from two different locations

174 / 491

Category: Transmission of Power from the Power Station to the Consumer

174. (A) Electric power is transmitted at high voltages to minimize energy loss in transmission lines.
(R) According to the formula $P_{\text{loss}} = I^2 R$, reducing current $I$ by increasing voltage $V$ decreases the power loss for a given power transmission.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

175 / 491

Category: Live Wire

175. (A) The earth pin in a three-pin plug is made longer than the live and neutral pins so that it connects first to ensure safety.
(R) The earth connection prevents electric shock by providing a low-resistance path for current in case of appliance defects.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

176 / 491

Category: Parallel Circuits:

176. In a parallel connection, what happens if one bulb stops glowing?

a) All other bulbs also stop glowing

b) The remaining bulbs glow brighter

c) The remaining bulbs continue to glow unaffected

d) The circuit breaks completely

177 / 491

Category: Power Distribution to a House

177. Why are the neutral and earth wires connected together at the local sub-station?

a) To increase the voltage difference between them

b) To decrease the resistance of the neutral wire

c) To ensure they are at the same potential (\$0 V\$)

d) To separate the return path of current from the source

178 / 491

Category: Practical Questions and Problems

178. Why is earthing of an electric appliance only effective if the fuse is connected to the live wire?

a) Because the live wire carries current at higher voltage.

b) Because the neutral wire cannot interrupt the circuit.

c) Because the earth wire provides an alternate path for current.

d) Because the fuse will blow only when excess current flows through the live wire.

179 / 491

Category: COLOUR CODING OF WIRES IN A CABLE

179. A three-core flexible cable is used in an electrical appliance. If the live wire insulation is brown, what should be the colour of the neutral and earth wires respectively?

a) Brown and blue

b) Blue and green

c) Green and black

d) Black and red

180 / 491

Category: Function of Fuse

180. (A) A fuse wire is made of an alloy of lead and tin because it has a low melting point.
(R) The low melting point of the alloy ensures that the fuse wire melts quickly when excessive current flows, breaking the circuit.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

181 / 491

Category: CIRCUITS WITH DUAL CONTROL SWITCHES (STAIRCASE WIRING)

181. Why should dual control switches never be operated with wet hands?

a) It may rust the switch contacts

b) Water can damage the bulb filament

c) Moisture creates a conductive path for current \�em It increases power consumption

182 / 491

Category: Transmission of Power from the Power Station to the Consumer

182. (A) The voltage from the generating station is stepped up to $132 \text{ kV}$ for transmission.
(R) Higher transmission voltage reduces the loss of energy in the form of heat in the line wires.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

183 / 491

Category: Working Mechanism

183. In a bicycle, what component is most directly involved in its working mechanism for movement?

a) The handlebar grip

b) The paint color

c) The chain and gears

d) The bell

184 / 491

Category: The Role of Fuse in Household Circuits

184. (A) A fuse wire made of copper with a radius of 0.5 mm and current rating of 10 A will melt when the current exceeds its safe limit.
(R) Copper has a high melting point and low specific resistance, making it unsuitable for use as a fuse wire.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

185 / 491

Category: Main Fuse and Meter

185. Which property makes a material suitable for use as a fuse wire?

a) High conductivity and high melting point

b) Low conductivity and high melting point

c) Low melting point and high resistance

d) High conductivity and low resistance

186 / 491

Category: Power Distribution to a House

186. In the sequence of wires stretched from one pole to another, which wire is placed at the topmost position?

a) Neutral wire

b) Live (phase) wire

c) Earth wire

d) Street light live wire

187 / 491

Category: Circuit Diagrams for Connecting Appliances

187. (A) In a household ring system of wiring, connecting appliances in parallel ensures that the voltage across each appliance remains 220 V regardless of the number of appliances in operation.
(R) The ring system provides two separate paths for current to reach each appliance, effectively reducing the resistance and maintaining consistent voltage.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

188 / 491

Category: Dual Control Switches and Staircase Wiring

188. What is the primary advantage of using dual control switches in staircase wiring compared to a single-pole switch?

a) They consume less power than single-pole switches

b) They allow control of the appliance from two different locations

c) They are cheaper to install than single-pole switches

d) They prevent electrical surges more effectively

189 / 491

Category: Appliance Earthing

189. (A) Earthing prevents a person from getting an electric shock when the live wire comes in contact with the metallic case of a faulty appliance.
(R) The earth wire provides a low-resistance path for the current to flow, causing the fuse to blow and disconnecting the appliance from the power supply.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

190 / 491

Category: Appliance Earthing

190. (A) The earth pin in a three-pin plug is longer and thicker to ensure the appliance's metallic case is earthed before the live connection is made.
(R) A longer earth pin ensures that even if the appliance is faulty, the user will not receive an electric shock because the fuse blows off before the live connection is established.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

191 / 491

Category: Current Rating

191. What does it mean if the current rating of a fuse is 5 A?

a) It means the fuse will conduct exactly 5 A current

b) It means the fuse will safely carry up to 5 A and melt if current exceeds this value

c) It means the fuse must carry at least 5 A

d) It means the fuse has a resistance of 5 ohms

192 / 491

Category: Appliance Earthing

192. What is the colour code for the insulation on the earth wire in a three-core flexible cable?

a) Red

b) Black

c) Blue

d) Green

193 / 491

Category: TRANSMISSION OF POWER FROM THE GENERATING STATION TO THE CONSUMER

193. A city substation receives power at $11 \text{ kV}$ and steps it down to $220 \text{ V}$ for domestic use. If the total resistance of the distribution lines from the substation to the consumers is $0.5 \Omega$, what is the power loss when supplying $100 \text{ kW}$ of power to a residential area?

a) 105.2 kW

b) 103.3 kW

c) 108.4 kW

d) 110.5 kW

194 / 491

Category: Three-Pin Plug and Socket

194. What is the purpose of the earth pin being thicker and longer in a three-pin plug?

a) To provide better insulation

b) To make the plug look more robust

c) To ensure the earth connection is made first and prevent incorrect insertion

d) To reduce manufacturing costs

195 / 491

Category: Step-Up and Step-Down Transformers

195. A step-up transformer has an efficiency of 98\%. It steps up the voltage from $11 \text{ kV}$ to $220 \text{ kV}$. If the input power is $100 \text{ MW}$, what is the power lost in the transformer?

a) 1 MW

b) 1.5 MW

c) 2 MW

d) 2.5 MW

196 / 491

Category: Live Wire

196. Why must the switch and fuse be connected in the live wire rather than the neutral wire in an electrical circuit?

a) To reduce voltage fluctuation in the appliance

b) To prevent the neutral wire from overheating

c) To ensure complete disconnection of current when the switch is off or fuse blows

d) To provide better earthing for the appliance

197 / 491

Category: Avoid Wet Hands:

197. A person gets an electric shock while using a faulty appliance. Which of the following situations would most likely prevent this shock if corrected?

a) Poor insulation of wires

b) Touching the appliance with wet hands

c) No earthing of the appliance

d) No fuse provided with the appliance

198 / 491

Category: Avoid Wet Hands:

198. A person inserts a plug into a socket with wet hands. What is the primary risk in this scenario?

a) The plug pins may bend or break

b) The socket may overheat due to increased resistance

c) Electric current may pass through the person's body

d) The appliance may operate at reduced efficiency

199 / 491

Category: Live Wire

199. What could happen if there is a loose connection in the live wire of an electrical appliance?

a) Appliance operates at lower efficiency

b) Appliance consumes less power

c) Sparking and burning of socket or plug

d) No noticeable effect on the appliance

200 / 491

Category: Earthing (Grounding)

200. (A) Earthing of an appliance with a metallic case prevents electric shock to the user if the live wire comes in contact with the case.
(R) The earth wire provides a low-resistance path for the current to flow, causing the fuse to blow and disconnect the circuit.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

201 / 491

Category: Live Wire

201. Why is it dangerous to touch a bare live wire when standing on a wet floor compared to a dry floor?

a) Wet floor increases body's insulation properties

b) Dry floor completely blocks any current flow

c) Water reduces resistance, allowing greater current through the body

d) Wetness decreases the voltage of the live wire

202 / 491

Category: Power Generation

202. Consider power being transmitted through four transformation stages (11kV→132kV→33kV→11kV→220V). If each transformer is 98\% efficient, what is the overall efficiency of the entire transformation process?

a) 98\%

b) 96.04\%

c) 92.2\%

d) 90.1\%

203 / 491

Category: Practical Questions and Problems

203. In a staircase wiring setup using dual control switches, how does the switching mechanism allow the light to be controlled from both ends of the staircase?

a) By using a parallel circuit connection.

b) By alternating the current flow direction between switches.

c) By connecting both switches to the same terminal.

d) By using a special type of switch called dual control switch.

204 / 491

Category: Circuit Diagrams for Connecting Appliances

204. A household has two bulbs rated at 220 V each. If they are mistakenly connected in series to a 440 V supply, what happens to their operation? (Assume equal resistance for both bulbs.)

a) Both bulbs glow at their rated brightness.

b) One bulb glows brighter, and the other does not glow.

c) Both bulbs glow dimmer than their rated brightness.

d) The bulbs burn out due to overvoltage.

205 / 491

Category: Types of Fuses

205. In a common fuse arrangement, why is the fuse wire placed in a porcelain holder?

a) To conduct electricity efficiently

b) To insulate the fuse wire from accidental contact

c) To increase the melting point of the fuse wire

d) To make the fuse reusable after it blows

206 / 491

Category: Main Fuse and Meter

206. Why should the main fuse always be connected in the live wire rather than the neutral wire in a household circuit?

a) To reduce power consumption

b) To ensure the meter records energy correctly

c) To protect the appliance even when the fuse blows

d) To prevent electric shocks by disconnecting the live supply

207 / 491

Category: COLOUR CODING OF WIRES IN A CABLE

207. (A) The earth wire in a three-core flexible cable is always colored green to ensure it is connected first due to its longer and thicker pin in the plug.
(R) The earth wire's primary function is to provide a low-resistance path for fault currents to prevent electric shocks.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

208 / 491

Category: Safety through Earthing

208. Why are high tension wires made by twisting together multiple thin insulated wires instead of using a single thick wire?

a) To reduce the overall weight of the wires

b) To make the wires more flexible and easier to install

c) To increase the surface area for better heat dissipation

d) To decrease the cost of manufacturing the wires

209 / 491

Category: Earthing (Grounding)

209. What is the purpose of using a mixture of charcoal and salt around the copper plate in local earthing?

a) To increase the mechanical strength of the copper plate

b) To prevent corrosion of the copper plate

c) To enhance conductivity and reduce soil resistance for better earthing

d) To provide insulation to the copper plate

210 / 491

Category: TRANSMISSION OF POWER FROM THE GENERATING STATION TO THE CONSUMER

210. If a transmission line has a resistance of 5 ohms and carries a current of 500 A, what is the energy loss per hour due to heating in the line?

a) 1250 MJ

b) 2250 MJ

c) 4500 MJ

d) 9000 MJ

211 / 491

Category: Circuit Diagrams for Connecting Appliances

211. What is the correct arrangement of pins in a three-pin plug as per standard wiring practices?

a) Earth at bottom, Live on left, Neutral on right

b) Earth at top, Neutral on left, Live on right

c) Earth at top, Live on left, Neutral on right

d) Live at top, Neutral on left, Earth on right

212 / 491

Category: Working Mechanism

212. In a properly wired dual control switch system where switch S$_1$ is currently making 'ba' connection and S$_2$ is making 'bc' connection (bulb off), what would a voltmeter read when connected between terminal 'a' of S$_1$ and terminal 'c' of S$_2$?

a) 0 V

b) Half of mains voltage

c) Full mains voltage

d) Cannot be determined without bulb resistance

213 / 491

Category: Avoid Wet Hands:

213. Why should you avoid touching a switch with wet hands?

a) It increases the resistance of the circuit.

b) It creates a conducting path for current to pass through the body.

c) It reduces the voltage of the appliance.

d) It prevents the switch from turning on.

214 / 491

Category: Avoid Wet Hands:

214. Why must hands be dry while inserting a plug into a socket?

a) To ensure a tight connection.

b) To prevent dust accumulation.

c) To avoid completing an unintended circuit through the body.

d) To increase the lifespan of the plug.

215 / 491

Category: Reason for connecting the fuse in the live wire

215. An appliance rated 2 kW at 220 V requires a fuse of what current rating?

a) 5 A

b) 10 A

c) 15 A

d) 20 A

216 / 491

Category: Proper Insulation

216. Why is the earthing of an electrical appliance important?

a) It prevents the appliance from getting wet.

b) It ensures the appliance operates at maximum efficiency.

c) It provides a safe path for excess current to prevent electric shock or fire.

d) It reduces the electricity bill by conserving energy.

217 / 491

Category: Step-Up and Step-Down Transformers

217. At what stage in power transmission is the voltage stepped down from $33 \text{ kV}$ to $11 \text{ kV}$ for distribution?

a) Generating station

b) Main sub-station

c) Intermediate sub-station

d) City sub-station

218 / 491

Category: Working Mechanism

218. (A) A dual control switch allows turning a bulb on/off from two different locations by changing the connection between terminals.

(R) The change in connection is achieved using a spring metal strip that alternately connects terminal 'b' to either 'a' or 'c' based on the switch position.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

219 / 491

Category: Power Generation

219. At what voltage and frequency is electric power typically generated at the power generating station?

a) $5 \text{ kV}, 60 \text{ Hz}$

b) $11 \text{ kV}, 50 \text{ Hz}$

c) $33 \text{ kV}, 50 \text{ Hz}$

d) $132 \text{ kV}, 25 \text{ Hz}$

220 / 491

Category: Connection of all appliances (bulb, fan, socket, etc.) with the mains

220. What is a critical safety precaution when inserting a plug into a socket?

a) Insert the plug slowly with wet hands to avoid sparks.

b) Ensure hands are dry and plug pins fit tightly.

c) Use gloves while inserting the plug for better grip.

d) Plug pins should loosely fit to allow easy removal.

221 / 491

Category: Power Generation

221. What device is used to step up the voltage from $11 \text{ kV}$ to $132 \text{ kV}$ at the generating station?

a) Step-down transformer

b) Power converter

c) Step-up transformer

d) Inverter

222 / 491

Category: Function of Fuse

222. Why must a fuse always be connected in the live wire rather than the neutral wire in an AC circuit?

a) It reduces power consumption when the fuse blows

b) It makes the fuse last longer

c) It prevents the appliance from remaining at high potential when the fuse blows

d) It allows the circuit to work with lower voltage appliances

223 / 491

Category: Three-Pin Plug and Socket

223. Why are high tension wires made by twisting together multiple thin insulated wires instead of using a single thick wire?

a) To increase the flexibility of the wire.

b) To reduce the overall cost of the wire.

c) To provide better insulation against electric shocks.

d) To increase the surface area for improved heat dissipation.

224 / 491

Category: Main Fuse and Meter

224. (A) The main fuse should always be connected in the live wire to ensure safety and proper functioning of the circuit.
(R) Connecting the fuse in the neutral wire can lead to the appliance remaining at a high potential even after the fuse blows, posing an electric shock hazard.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

225 / 491

Category: Advantages of connecting the appliances in parallel

225. (A) Each appliance connected in parallel operates at its rated voltage.
(R) In a parallel connection, the voltage remains constant across all appliances.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

226 / 491

Category: Working Mechanism

226. (A) A dual control switch allows controlling a bulb from two different locations.
(R) The dual control switch uses two switches $S_1$ and $S_2$, which can independently turn the bulb 'on' or 'off'.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

227 / 491

Category: Step-Up and Step-Down Transformers

227. (A) A step-up transformer increases the voltage to reduce energy loss during transmission.
(R) Higher transmission voltage reduces current, minimizing energy loss as heat in transmission lines ($P = VI$ and $I = \frac{P}{V}$).

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

228 / 491

Category: Neutral Wire

228. (A) The neutral wire is connected to the right pin in a three-pin plug marked 'N'.
(R) The neutral wire provides the return path for the current in an electrical circuit.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

229 / 491

Category: Function of Fuse

229. (A) A fuse wire melts when the current exceeds its rating.
(R) The melting of the fuse wire is due to the heating effect of current.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

230 / 491

Category: Main Fuse and Meter

230. Why is the fuse connected in the live wire and not in the neutral wire?

a) To reduce power consumption

b) To ensure the appliance remains connected to the supply

c) To prevent electric shock by disconnecting the live wire

d) To increase the efficiency of the appliance

231 / 491

Category: CIRCUITS WITH DUAL CONTROL SWITCHES (STAIRCASE WIRING)

231. In a staircase wiring setup, what is the primary function of dual control switches?

a) To regulate voltage supply to the bulb

b) To allow switching ON/OFF from two different points

c) To increase the brightness of the bulb

d) To reduce power consumption of the circuit

232 / 491

Category: Current Rating

232. Can a fuse rated 8 A be used with an electrical appliance of rating 5 kW, 200 V?

a) Yes, because 5 kW is within the safe range for an 8 A fuse

b) No, because the appliance draws 25 A which exceeds the fuse's rating

c) Yes, because 200 V is compatible with the fuse

d) No, because the appliance power is too low for the fuse

233 / 491

Category: Circuit Diagrams for Connecting Appliances

233. Consider a household circuit where multiple appliances (bulb, fan, socket) are connected in parallel to the mains using a ring system. If one appliance's fuse blows due to a fault, what happens to the other appliances in the same ring circuit?

a) The other appliances stop working immediately.

b) The other appliances continue to work normally.

c) The other appliances receive higher voltage and may get damaged.

d) The main fuse burns out, shutting down all appliances.

234 / 491

Category: Appliance Earthing

234. What happens if the metallic case of an appliance is not properly earthed and the live wire comes in contact with it due to insulation failure?

a) The appliance will continue working normally without any issue.

b) The appliance may overheat but no shock hazard exists.

c) A person touching the appliance will receive a fatal electric shock.

d) The fuse will blow immediately even without earthing.

235 / 491

Category: Three-Pin Plug and Socket

235. (A) The earth pin in a three-pin plug is longer than the live and neutral pins to ensure that it connects first and disconnects last during insertion and removal of the plug.
(R) This design ensures user safety by guaranteeing that the appliance is grounded before current flows through the live wire, and the grounding remains intact until after the current stops flowing.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

236 / 491

Category: SAFETY PRECAUTIONS WHILE USING THE ELECTRICITY

236. (A) A 1.5 kW water pump rated at 220 V should always use a fuse with a current rating higher than its running current of 6.8 A to prevent overheating and ensure safety.
(R) Electric appliances with motors draw significantly higher starting currents compared to their running currents, so the fuse rating must account for the initial surge to avoid blowing during startup.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

237 / 491

Category: Earthing (Grounding)

237. Why is it necessary to remove paint from the metallic case of an appliance before earthing?

a) To improve the aesthetic appearance of the appliance

b) To ensure electrical conductivity between the earth wire and the metallic case

c) To protect the appliance from corrosion

d) To reduce the weight of the appliance

238 / 491

Category: Power Generation

238. A power generating station produces 50 MW of power at 11 kV. If the transmission line has a resistance of 10 Ω, what percentage of power would be lost if it were transmitted directly without stepping up the voltage?

a) 413.2\%

b) 2.87\%

c) 27.5\%

d) 92.4\%

239 / 491

Category: Household Wiring (Ring System)

239. What is one major advantage of using the ring system in household wiring?

a) It increases the voltage supplied to appliances

b) It allows appliances to be connected in series

c) It reduces wiring costs by using lower-capacity wires for the main ring

d) It requires no fuses for individual appliances

240 / 491

Category: Fuse and Switch Locations

240. What is the primary reason for connecting a switch in the live wire instead of the neutral wire?

a) To reduce power consumption

b) To increase the lifespan of the switch

c) To prevent electric shock when the switch is off

d) To allow current flow in both directions

241 / 491

Category: Three-Pin Plug and Socket

241. A metallic case of an appliance is not earthed properly. What will happen if the live wire touches the case due to a break in insulation?

a) The fuse will blow immediately, disconnecting the circuit.

b) The appliance will continue to work normally without any issue.

c) The person touching the appliance may receive a fatal electric shock.

d) The neutral wire will compensate for the fault, preventing any danger.

242 / 491

Category: Power Generation

242. At an intermediate substation receiving 33 kV, if the step-down transformer has a turns ratio of 30:1 and supplies power to light industries, what voltage does it output considering no losses?

a) 220 V

b) 11 kV

c) 1.1 kV

d) 330 V

243 / 491

Category: Earth Wire

243. (A) The earth wire in a three-pin plug is thicker and longer than the live and neutral wires.
(R) The earth pin being thicker ensures it cannot be inserted into the live or neutral socket holes by mistake, while its length ensures the earth connection is made first for safety.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

244 / 491

Category: Fuse and Switch Locations

244. What is the correct current rating for a fuse to be used with a 4 kW, 200 V appliance?

a) 5 A

b) 10 A

c) 15 A

d) 20 A

245 / 491

Category: Parallel Circuits:

245. Three identical bulbs are connected in parallel to a 220 V mains supply. Each bulb is rated 220 V, 60 W. What is the total power consumed by the circuit when all bulbs are switched on?

a) 60 W

b) 120 W

c) 180 W

d) 240 W

246 / 491

Category: TRANSMISSION OF POWER FROM THE GENERATING STATION TO THE CONSUMER

246. (A) Electric power is transmitted at high voltages to minimize energy loss in transmission lines.
(R) According to $P = I^2 R$, higher voltage reduces the current, thereby decreasing the heat loss in conductors.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

247 / 491

Category: Reason for connecting the fuse in the live wire

247. (A) A fuse should always be connected in the live wire of an electrical circuit to ensure safety.
(R) Connecting the fuse in the neutral wire leaves the appliance at a high potential even after the fuse blows, risking electric shock.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

248 / 491

Category: Advantages of connecting the appliances in parallel

248. Which benefit does the ring system provide for electrical wiring?

a) Requires thicker wires for all connections \ifxetexcurrent voltage remains constant regardless of appliance count

b) Current flows through only one path

c) Reduces wiring cost and provides independent operation

249 / 491

Category: Safety through Earthing

249. Why is a mixture of charcoal and salt used around the copper plate in local earthing?

a) To insulate the copper plate from the ground

b) To increase the resistance of the earthing system

c) To prevent corrosion of the copper plate

d) To ensure good contact and conductivity with the earth

250 / 491

Category: Three-Pin Plug and Socket

250. What is the purpose of making the earth pin in a three-pin plug thicker than the other two pins?

a) To reduce the resistance of the earth connection.

b) To ensure the earth connection is made before the live and neutral connections.

c) To prevent the earth pin from being inserted into live or neutral holes.

d) To make the plug more durable.

251 / 491

Category: Disadvantages of connecting the appliances in series

251. (A) When appliances are connected in series, the voltage across each appliance is less than its rated voltage.
(R) The total voltage of the source gets divided among all appliances connected in series.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

252 / 491

Category: Step-Up and Step-Down Transformers

252. Why do transformers only work with alternating current (AC)?

a) Because AC has higher frequency than DC

b) Because DC produces more heat than AC

c) Because transformers need a changing magnetic field to function

d) Because AC is easier to generate than DC

253 / 491

Category: HOUSE WIRING (RING SYSTEM)

253. A ring wiring system has two possible paths from the distribution box to an appliance. Path 1 has a resistance of 0.8 Ω and Path 2 has 1.2 Ω. If the appliance draws 10 A current, what is the approximate current flowing through Path 1?

a) 3.2 A

b) 4.8 A

c) 6.0 A

d) 7.2 A

254 / 491

Category: Proper Insulation

254. What should be the colour of the insulation on the live wire in a properly insulated cable?

a) Red

b) Blue

c) Green

d) Brown

255 / 491

Category: Current Rating

255. An electric kettle is rated 3 kW, 250 V. Can this kettle be used in a circuit containing a fuse of current rating 13 A?

a) No, because the kettle draws more current than the fuse rating.

b) Yes, because the kettle's current draw is within the fuse's limit.

c) No, because the voltage ratings do not match.

d) Yes, but it may cause overheating of the fuse.

256 / 491

Category: Reason for connecting the fuse in the live wire

256. What happens if a fuse is connected in the neutral wire instead of the live wire?

a) The appliance becomes more efficient

b) It saves electricity

c) The circuit automatically resets

d) The appliance remains connected to live wire creating shock hazard

257 / 491

Category: Energy Consumption

257. If an appliance consumes 2 kWh of energy daily for 30 days, and the cost of electricity is \$0.12 per kWh, what is the total cost incurred over 30 days?

a) \$3.60

b) \$7.20

c) \$14.40

d) \$9.60

258 / 491

Category: Circuit Diagrams for Connecting Appliances

258. What is the primary purpose of earthing in an electrical appliance?

a) To increase the appliance's efficiency

b) To reduce electricity consumption

c) To provide a safe path for fault current

d) To make the appliance lighter

259 / 491

Category: Earth Wire

259. (A) The earth pin in a three-pin plug is longer and thicker than the live and neutral pins.
(R) This ensures that the earth connection is made first when the plug is inserted into the socket, providing immediate safety in case of a fault.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

260 / 491

Category: Step-Up and Step-Down Transformers

260. Why does increasing the transmission voltage help reduce energy losses during power transmission?

a) Higher voltage means less insulation needed

b) It decreases the current, reducing $I^2 R$ losses \transformers can work more efficiently at higher voltages

c) Higher voltage decreases resistance of transmission lines

261 / 491

Category: Earthing (Grounding)

261. Which feature of the earth pin in a three-pin plug ensures user safety by preventing incorrect insertion?

a) Its shorter length ensures easy insertion in any socket hole.

b) It is made of a different material than the other pins.

c) It has a flexible design to fit loosely in the socket.

d) It is colored differently to distinguish it from other pins.

262 / 491

Category: Function of Fuse

262. In a household circuit, a geyser rated at 3000 W at 230 V is to be protected by a fuse. Which of the following fuse ratings would be most appropriate for this appliance?

a) 5 A

b) 10 A

c) 13 A

d) 15 A

263 / 491

Category: Safety through Earthing

263. (A) Local earthing involves burying a copper plate in the ground to provide a safe path for excessive current.
(R) The mixture of charcoal and salt around the copper plate improves conductivity by keeping the ground damp.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

264 / 491

Category: Current Rating

264. (A) The current rating of a fuse is determined by its material, length, and thickness.
(R) A thicker fuse wire has lower resistance and can carry more current without melting.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

265 / 491

Category: Disadvantages of connecting the appliances in series

265. Why does adding another appliance in series reduce the current in the circuit?

a) It reduces the total voltage of the circuit.

b) The power supply stops working.

c) The total resistance of the circuit increases.

d) The appliances short-circuit.

266 / 491

Category: Dual Control Switches and Staircase Wiring

266. In a dual control switch setup for staircase wiring, when bulb is in 'off' position, what must be the configuration of switches $S_1$ and $S_2$?

a) Both switches have $ba$ connections

b) Both switches have $bc$ connections

c) One switch has $ba$ and other has $bc$

d) One switch has $ba$ and other has no connection

267 / 491

Category: Choosing the Correct Fuse

267. An electric geyser has a power rating of 5 kW and operates at 220 V. What should be the current rating of the fuse used for this appliance?

a) 10 A

b) 15 A

c) 20 A

d) 25 A

268 / 491

Category: Working Mechanism

268. (A) In a dual control switch arrangement, operating either switch $S_1$ or $S_2$ can independently turn the bulb 'on' or 'off'.
(R) The dual control switch mechanism changes the connections between terminals 'a', 'b', and 'c', ensuring the live wire is safely managed during switching operations.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

269 / 491

Category: Appliance Earthing

269. Why is the earth pin in a three-pin plug made longer and thicker compared to the live and neutral pins?

a) To make it easier to insert into the socket.

b) To ensure the earth connection is made first and prevent wrong insertion.

c) To reduce the resistance of the earth connection.

d) To distinguish it visually from the other pins.

270 / 491

Category: Live Wire

270. Why should the switch and fuse always be connected to the live wire?

a) To save electricity costs

b) To make the appliance more efficient

c) To ensure easy identification of the wire

d) To safely interrupt the circuit when needed

271 / 491

Category: Current Rating

271. A fuse is rated 8 A. Can it be used with an electrical appliance of rating 5 kW, 200 V?

a) Yes, because the appliance draws less current than the fuse rating.

b) No, because the appliance draws more current than the fuse rating.

c) Yes, but only for short durations.

d) No, because the voltage of the appliance is different.

272 / 491

Category: Transmission of Power from the Power Station to the Consumer

272. What type of current is used for power transmission from the generating station?

a) Direct Current (DC)

b) Alternating Current (AC)

c) Both AC and DC

d) Pulsating DC

273 / 491

Category: Avoid Wet Hands:

273. What is the primary risk of operating an electrical appliance with wet hands?

a) The appliance may overheat.

b) The appliance may stop working permanently.

c) Electric current may pass through the body, causing shock.

d) The fuse may blow frequently.

274 / 491

Category: Disadvantages of connecting the appliances in series

274. Two electric heaters rated 1000W each at 220V are connected in series to a 440V supply. How does their performance get affected?

a) Both heaters work normally at rated power

b) One heater works normally while the other doesn't

c) Both heaters consume less power than rated

d) Both heaters stop working immediately

275 / 491

Category: Proper Insulation

275. In a household circuit, the fuse is always placed in the live wire before connecting to any appliance. What would be the consequence if the fuse were incorrectly placed in the neutral wire instead?

a) The appliance will stop working permanently

b) It prevents electric shock completely

c) The circuit remains energized, increasing shock risk

d) It reduces the current-carrying capacity

276 / 491

Category: Avoid Wet Hands:

276. Which of the following is a general safety measure regarding hands when handling electrical appliances?

a) Wash hands before touching

b) Keep hands moisturized

c) Ensure hands are always dry

d) Use hand sanitizer frequently

277 / 491

Category: Earthing (Grounding)

277. Why must paint be removed from the metallic case of an appliance before earthing?

a) To make the appliance look cleaner

b) To prevent rusting of the metallic case

c) To improve the durability of the earth wire

d) To ensure proper electrical contact by removing insulating paint

278 / 491

Category: COLOUR CODING OF WIRES IN A CABLE

278. Which wire's insulation is green in a three-core flexible cable?

a) Live wire

b) Neutral wire

c) Earth wire

d) Fuse wire

279 / 491

Category: FUSE

279. A fuse wire has a current rating of 5 A and radius 0.4 mm. If the radius is halved while keeping all other parameters constant, what will be the new current rating of the fuse wire?

a) 1.77 A

b) 2.50 A

c) 3.54 A

d) 5.00 A

280 / 491

Category: Choosing the Correct Fuse

280. A 5 kW electric heater is connected to a 250 V mains supply. The current drawn by the heater is calculated, and an appropriate fuse needs to be selected. Which of the following fuses would be most suitable for this setup?

a) 15 A

b) 20 A

c) 25 A

d) 30 A

281 / 491

Category: Avoid Wet Hands:

281. (A) Touching an electrical appliance with wet hands increases the risk of electric shock.
(R) Water is a good conductor of electricity due to the presence of dissolved ions.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

282 / 491

Category: Proper Insulation

282. What is the purpose of adding charcoal and salt mixture around the copper plate in local earthing?

a) To make the earthing setup look neat.

b) To reduce the cost of earthing materials.

c) To improve conductivity between the plate and the ground.

d) To prevent corrosion of the copper plate.

283 / 491

Category: Household Wiring (Ring System)

283. Why is earthing necessary for metallic cases of electrical appliances?

a) To provide an alternative path for extra current during normal operation

b) To prevent any electrical connection between live and neutral wires

c) To protect users from electric shock due to insulation failure

d) To increase the efficiency of the appliance

284 / 491

Category: Choosing the Correct Fuse

284. A device requires a current of 12 A at 240 V. The available fuses are rated at 10 A, 15 A, 20 A, and 25 A. Which fuse should be used to ensure safety while allowing the device to operate normally?

a) 10 A

b) 15 A

c) 20 A

d) 25 A

285 / 491

Category: Types of Fuses

285. A rewirable fuse is rated for 5 A and is used in a circuit supplying power to a fan. If the current exceeds 7 A, calculate the approximate ratio of temperature rise when compared to its normal operating current.

a) 1.44

b) 1.96

c) 2.00

d) 2.50

286 / 491

Category: Types of Fuses

286. A technician incorrectly connects a rewirable fuse in the neutral wire instead of the live wire in a household circuit. What is the primary risk associated with this incorrect connection?

a) The fuse will not blow under any condition

b) The circuit efficiency will decrease

c) Risk of electric shock persists even after the fuse blows

d) The appliance will consume more power

287 / 491

Category: Main Fuse and Meter

287. A fuse wire with a specific resistance $\rho$ of $1.7 \times 10^{-8} \, \Omega m$, length $l = 5 \, cm$, and radius $r = 0.5 \, mm$ is used in a circuit. What current would cause the fuse to melt if the melting temperature corresponds to a heat generation rate of $0.1 \, W$?

a) 5.00 A

b) 7.50 A

c) 9.62 A

d) 12.00 A

288 / 491

Category: Dual Control Switch

288. Where is a dual control switch commonly used?

a) In refrigerators

b) At the top and bottom of a staircase

c) Inside air conditioners \� In power plants

289 / 491

Category: Dual Control Switch

289. A dual control switch is primarily used for:

a) Controlling a single appliance from multiple locations

b) Increasing the voltage supplied to an appliance

c) Reducing the current flow in a circuit

d) Connecting multiple appliances in series

290 / 491

Category: Power Generation

290. What is the nature of the current transmitted from the power station to the consumer?

a) Direct current (d.c.)

b) Pulsating current

c) Alternating current (a.c.)

d) Static current

291 / 491

Category: Appliance Earthing

291. Why is earthing important for an electrical appliance with a metallic case?

a) To increase the efficiency of the appliance

b) To prevent the fuse from blowing

c) To ensure safety by diverting fault current to the ground

d) To reduce the power consumption of the appliance

292 / 491

Category: CIRCUITS WITH DUAL CONTROL SWITCHES (STAIRCASE WIRING)

292. What is the primary safety precaution to consider while using dual control switches?

a) Always operate both switches simultaneously to avoid short circuits.

b) Ensure the switches are made of plastic to prevent electric shocks.

c) Avoid touching switches with wet hands to prevent electric shock.

d) Use insulated gloves when operating the switches.

293 / 491

Category: FUSE

293. (A) For a fuse wire of radius $r$, the temperature rise $\Delta T$ is inversely proportional to $r^3$ when the current exceeds its rating.
(R) The heating effect of current in a fuse wire depends on its resistance, which is inversely proportional to its cross-sectional area.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

294 / 491

Category: Working Mechanism

294. Consider a staircase wiring setup with switches S$_1$ and S$_2$ controlling a bulb. Initially, the bulb is off with S$_1$ in 'ba' position and S$_2$ in 'bc' position. Which sequence of operations will turn the bulb ON then OFF without leaving it in its initial state?

a) Flip S$_1$, then flip S$_1$ again

b) Flip S$_2$, then flip S$_1$

c) Flip S$_1$, then flip S$_2$ twice

d) Flip S$_2$ twice, then flip S$_1$ once

295 / 491

Category: Power Generation

295. Which device is used to increase the voltage at the generating station?

a) Step-down transformer

b) Alternator

c) Step-up transformer

d) Rectifier

296 / 491

Category: Parallel Circuits:

296. Which of the following is an advantage of connecting appliances in parallel?

a) Voltage divides among appliances

b) Total resistance increases with more appliances

c) Appliances operate independently at rated voltage

d) Appliances must work simultaneously

297 / 491

Category: TRANSMISSION OF POWER FROM THE GENERATING STATION TO THE CONSUMER

297. A power station generates $500 \text{ MW}$ of power at $11 \text{ kV}$. If the transmission voltage is stepped up to $132 \text{ kV}$ using a transformer, what will be the percentage reduction in power loss if the resistance of the transmission line is $10 \Omega$?

a) 95.4\%

b) 97.8\%

c) 99.3\%

d) 98.5\%

298 / 491

Category: Power Generation

298. (A) Electric power is transmitted at higher voltages to minimize energy loss in transmission lines.

(R) According to $P = I^2 R$, lower current reduces the heat loss in the transmission lines.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

299 / 491

Category: Dual Control Switches and Staircase Wiring

299. What happens when the knob of a dual control switch is shifted to the left or down?

a) Terminal $b$ connects to terminal $a$

b) Terminal $b$ connects to terminal $c$

c) The circuit breaks permanently

d) The switch becomes non-functional

300 / 491

Category: Dual Control Switch

300. In a dual control switch setup for a long corridor, which configuration ensures that switching either switch changes the bulb’s state?

a) S1 set to 'ba' and S2 set to 'ba'

b) S1 set to 'bc' and S2 set to 'bc'

c) S1 set to 'ba' and S2 set to 'bc'

d) S1 and S2 set to any valid combination except 'off' mode

301 / 491

Category: Neutral Wire

301. (A) The switch must always be connected in the live wire and not in the neutral wire.
(R) Connecting the switch in the neutral wire keeps the appliance at high potential even when switched off, posing a risk of electric shock.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

302 / 491

Category: FUSE

302. Why is an alloy of lead and tin preferred for making fuse wires instead of copper or aluminum?

a) Higher conductivity

b) Lower cost

c) Lower melting point

d) Greater flexibility

303 / 491

Category: Main Fuse and Meter

303. A fuse is connected in the live wire rather than the neutral wire because:

a) To prevent damage to the appliance only

b) To protect the wiring from overheating

c) To ensure the appliance receives full voltage

d) To prevent electric shock by breaking the connection to the high potential point

304 / 491

Category: FUSE

304. In a household wiring system, where is the main fuse connected and why?

a) In the neutral wire after the kWh meter

b) In the live wire after the main circuit

c) In the earth wire for grounding

d) In the live wire after the kWh meter and before the main circuit

305 / 491

Category: SAFETY PRECAUTIONS WHILE USING THE ELECTRICITY

305. A water pump rated 2.2 kW, 220 V has a starting current of 12 A and running current of 8 A. What should be the minimum current rating of its fuse?

a) 6 A

b) 8 A

c) 15 A

d) 25 A

306 / 491

Category: The Role of Fuse in Household Circuits

306. Why must the fuse be connected in the live wire and not the neutral wire?

a) To reduce power consumption

b) To ensure the fuse does not melt unnecessarily

c) To prevent electric shock by disconnecting the appliance from high potential

d) To allow the fuse to work at higher voltages

307 / 491

Category: SAFETY PRECAUTIONS WHILE USING THE ELECTRICITY

307. Why is the earth pin in a three-pin plug made longer and thicker than the other two pins?

a) To save material costs

b) To make the plug aesthetically pleasing

c) To ensure faster power transmission

d) To prioritize grounding and prevent incorrect insertion

308 / 491

Category: Transmission of Power from the Power Station to the Consumer

308. At which substation is the voltage stepped down from $33 \text{kV}$ to $11 \text{kV}$ before supplying it to light industries and city substations?

a) Grid substation

b) Main substation

c) Intermediate substation

d) City substation

309 / 491

Category: Function of Fuse

309. What is the main function of a fuse in an electrical circuit?

a) To increase the current flow in the circuit

b) To reduce the voltage in the circuit

c) To measure the power consumption

d) To break the circuit when current exceeds the rated limit

310 / 491

Category: HOUSE WIRING (RING SYSTEM)

310. Which color is used for the live wire in the house wiring ring system as per standard conventions?

a) Light Blue

b) Green or Yellow

c) Brown or Red

d) Black

311 / 491

Category: Disadvantages of connecting the appliances in series

311. In a household, four lamps are connected in series. If one lamp burns out, what will happen to the other three lamps?

a) Only the faulty lamp stops working

b) All lamps continue to work but with reduced brightness

c) The other three lamps also stop working

d) The other two lamps burn brighter

312 / 491

Category: Safety Precautions in Household Circuits

312. Why is a Miniature Circuit Breaker (MCB) preferred over a traditional fuse in modern household circuits?

a) It requires manual replacement after tripping

b) It responds slower than a fuse during short circuits

c) It eliminates the need for connecting new fuse wires and offers quick response

d) It cannot be reset after a fault

313 / 491

Category: Household Wiring (Ring System)

313. If an electrical appliance with a metal casing develops a fault causing the live wire to come in contact with the casing, why does the earth wire prevent electric shock?

a) It insulates the user from the casing

b) It provides a low-resistance path for fault current to flow to the ground

c) It increases the resistance of the appliance

d) It reduces the voltage supplied to the appliance

314 / 491

Category: Proper Insulation

314. Why is local earthing done near the kWh meter?

a) To increase the voltage supply

b) To reduce electricity bills

c) To provide a path for excessive current to flow to the earth

d) To insulate the wires

315 / 491

Category: Three-Pin Plug and Socket

315. (A) The earth pin in a three-pin plug is made longer and thicker to ensure safety by completing the earth connection before the live and neutral connections are established.
(R) In case of a fault, the current flows through the earth wire, blowing the fuse and preventing electric shock.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

316 / 491

Category: The Role of Fuse in Household Circuits

316. What happens when the current in a household circuit exceeds the safe limit?

a) The fuse wire expands but does not break the circuit.

b) The fuse wire melts, breaking the circuit and stopping the current flow.

c) The fuse wire becomes thicker and reduces resistance.

d) The fuse wire emits light but continues conducting current.

317 / 491

Category: Choosing the Correct Fuse

317. Which type of fuse wire is most suitable for protecting a circuit with two ceiling fans (each 60 W) and four LED bulbs (each 10 W) operating at 220 V?

a) 1 A

b) 3 A

c) 5 A

d) 10 A

318 / 491

Category: HOUSE WIRING (RING SYSTEM)

318. What is the primary purpose of earthing an electrical appliance in the ring system?

a) To increase the voltage supplied to the appliance.

b) To reduce power consumption.

c) To provide a safe path for leakage current.

d) To enhance the conductivity of the circuit.

319 / 491

Category: Safety Precautions in Household Circuits

319. What is the primary reason for using an earth wire in household appliances with metallic cases?

a) To reduce the power consumption of the appliance

b) To prevent the appliance from overheating

c) To provide a low-resistance path for fault current to the ground

d) To increase the efficiency of the appliance

320 / 491

Category: Three-Pin Plug and Socket

320. Which hole in a three-pin socket is connected to the live wire of the electric supply?

a) The upper bigger hole

b) The hole on the left side

c) The hole on the right side

d) The central smaller hole

321 / 491

Category: Earthing (Grounding)

321. What is the purpose of adding a mixture of charcoal and salt around the copper plate in local earthing?

a) To increase the depth of the earthing pit

b) To make the copper plate rust-resistant

c) To create a conductive layer between the plate and the ground

d) To prevent water from entering the earthing pit

322 / 491

Category: Three-Pin Plug and Socket

322. Why must the hands be dry while inserting a plug into a socket?

a) To avoid making the plug slippery

b) To prevent corrosion of the plug pins

c) To reduce the chance of electric shock due to wetness conducting electricity

d) To maintain hygiene

323 / 491

Category: COLOUR CODING OF WIRES IN A CABLE

323. What would happen if you connect the live wire (brown) to the earth terminal of an appliance?

a) The appliance will work normally

b) The fuse will blow immediately

c) The appliance will not turn on

d) It may cause short circuit or electric shock

324 / 491

Category: Function of Fuse

324. Why is an alloy of lead and tin preferred for making fuse wires instead of copper?

a) Copper is more conductive

b) Copper is cheaper

c) Lead-tin alloy has a lower melting point

d) Copper wires are thicker

325 / 491

Category: Live Wire

325. (A) The live wire in an electrical appliance is insulated with red or brown colour.
(R) The colour coding helps in identifying the function of each wire for proper and safe connections.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

326 / 491

Category: Fuse and Switch Locations

326. Why is an MCB preferred over a traditional fuse in modern electrical circuits?

a) It is cheaper than a traditional fuse

b) It does not require any maintenance

c) It has a slower response time than a fuse

d) It can be reset after a fault without replacement

327 / 491

Category: Energy Consumption

327. In which unit does the electric meter in a house measure the electrical energy consumed, and what is its equivalent in joules?

a) Watt-hour (Wh), $3.6 \times 10^3$ J

b) Kilowatt-hour (kWh), $3.6 \times 10^5$ J

c) Kilowatt-hour (kWh), $3.6 \times 10^6$ J

d) Joule (J), $3.6 \times 10^6$ J

328 / 491

Category: SAFETY PRECAUTIONS WHILE USING THE ELECTRICITY

328. (A) Earthing of metallic cases in appliances prevents electric shock.
(R) Earthing provides a low-resistance path for leakage current to flow into the ground, preventing potential buildup on the appliance.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

329 / 491

Category: Safety through Earthing

329. (A) The earth wire is connected to the metallic case of an appliance to ensure that any leakage current flows directly to the ground.
(R) The earth wire provides a low-resistance path for the leakage current, which blows the fuse and prevents electric shock.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

330 / 491

Category: Three-Pin Plug and Socket

330. Which colour code is used for the neutral wire in a three-core flexible cable?

a) Red (or brown)

b) Black (or light blue)

c) Green

d) Yellow

331 / 491

Category: Earthing (Grounding)

331. What happens when a live wire comes in contact with the metallic case of a properly earthed appliance?

a) The appliance continues to function normally

b) The appliance gets damaged permanently

c) A heavy current flows to the ground and the fuse blows

d) The live wire insulation melts and repairs itself

332 / 491

Category: Step-Up and Step-Down Transformers

332. A transformer is used to step up the voltage from $11 \text{ kV}$ to $132 \text{ kV}$ for transmission. What happens to the current in this process, assuming ideal conditions and no power loss?

a) Current increases by a factor of 12

b) Current decreases by a factor of 12

c) Current remains unchanged

d) Current first increases then decreases

333 / 491

Category: Proper Insulation

333. A household appliance is connected to a three-core flexible cable with brown, blue, and green insulation. Which of the following correctly describes the purpose of twisting multiple thin wires together in the high tension wire part of this setup?

a) To reduce the overall cost of the wire

b) To decrease the flexibility of the wire

c) To increase the resistance of the wire

d) To provide a large surface area for better heat dissipation

334 / 491

Category: HOUSE WIRING (RING SYSTEM)

334. What is the standard voltage rating for household appliances in the ring system?

a) 110 V

b) 440 V

c) 220 V

d) 330 V

335 / 491

Category: Function of Fuse

335. Why is it unsafe to connect a fuse in the neutral wire of an appliance?

a) It increases resistance

b) Neutral wire carries no current

c) Appliance remains connected to the live wire

d) Fuse will not blow in neutral

336 / 491

Category: Connection of all appliances (bulb, fan, socket, etc.) with the mains

336. How are household electrical appliances connected to the mains supply?

a) In series

b) In parallel

c) Both in series and parallel

d) None of the above

337 / 491

Category: Connection of all appliances (bulb, fan, socket, etc.) with the mains

337. In a parallel circuit with a 5 A fuse, three appliances draw currents of 2 A, 1.5 A, and 1 A respectively. What happens if a fourth appliance drawing 1.5 A is added to the circuit?

a) The fuse blows, disconnecting all appliances

b) Only the fourth appliance stops working

c) The total current remains within limits, so all appliances work normally

d) The voltage across each appliance drops proportionally

338 / 491

Category: TRANSMISSION OF POWER FROM THE GENERATING STATION TO THE CONSUMER

338. What is the final stepped-down voltage supplied to domestic consumers?

a) $11 \text{ kV}$

b) $33 \text{ kV}$

c) $220 \text{ V}$

d) $132 \text{ kV}$

339 / 491

Category: Safety through Earthing

339. Why is it essential to earth the metallic case of an electrical appliance?

a) Prevents overheating of wires

b) Ensures proper functioning of the appliance

c) Protects against electric shock by diverting fault current

d) Increases the efficiency of the appliance

340 / 491

Category: Earthing (Grounding)

340. Why is it necessary to remove paint from the metallic case of an appliance before making an earth connection?

a) To improve the aesthetic appearance of the appliance

b) To prevent corrosion of the metallic case

c) To ensure proper insulation of the appliance

d) To establish a good electrical connection with the earth wire

341 / 491

Category: Three-Pin Plug and Socket

341. Why is the earth pin in a three-pin plug made longer and thicker than the live and neutral pins? Consider all technical reasons.

a) To make it visually distinct for color-blind users

b) To reduce manufacturing costs by using less material

c) To allow higher current flow during normal operation

d) For sequential connection and physical prevention of wrong insertion

342 / 491

Category: TRANSMISSION OF POWER FROM THE GENERATING STATION TO THE CONSUMER

342. A power generating station transmits 100 MW of power at 132 kV to minimize energy loss. If the same power were transmitted at 11 kV instead, how would the current in the transmission line change?

a) It would decrease by a factor of 12

b) It would remain the same

c) It would increase by a factor of 12

d) It would decrease by a factor of 6

343 / 491

Category: Dual Control Switch

343. What happens if a person at the top of the staircase operates switch S2 from 'bc' to 'ba' while the bulb is already on via S1?

a) Bulb remains on as S1 is still active

b) Bulb brightness doubles due to parallel paths

c) Bulb turns off as the circuit breaks

d) Short circuit occurs due to conflicting connections

344 / 491

Category: Safety through Earthing

344. Why is the earth pin in a three-pin plug made longer and thicker than the other two pins?

a) To make it easier to identify the earth connection

b) To provide structural strength to the plug

c) To ensure reliable and safer connectivity before live and neutral connections

d) To comply with international standards

345 / 491

Category: Power Distribution to a House

345. Why is the main switch in a residential power distribution system designed as a double-pole switch connected to both live and neutral wires instead of just the live wire?

a) To reduce energy consumption.

b) To allow higher current flow.

c) To ensure complete circuit isolation for safety.

d) To simplify wiring connections.

346 / 491

Category: Function of Fuse

346. A geyser has a power rating of 3000 W and operates at 220 V. What should be the current rating of the fuse used for this geyser?

a) 5 A

b) 10 A

c) 13 A

d) 15 A

347 / 491

Category: Disadvantages of connecting the appliances in series

347. What happens to the voltage across each appliance when connected in series?

a) Each appliance gets the full rated voltage.

b) The voltage is equally divided among all appliances.

c) The voltage divides according to the resistance ratio of the appliances.

d) No voltage is supplied to any appliance.

348 / 491

Category: Parallel Circuits:

348. In a household parallel circuit, two bulbs of resistances $R_1 = 110 \,\Omega$ and $R_2 = 220 \,\Omega$ are connected to a $220 \,V$ supply. What is the total power consumed by the circuit?

a) 330 W

b) 660 W

c) 880 W

d) 220 W

349 / 491

Category: Safety Precautions in Household Circuits

349. A household circuit uses 4 mm² copper wires rated for 30 A maximum. If the total connected load is 5.5 kW at 220 V, what could happen if all appliances operate simultaneously?

a) Wires will definitely melt immediately

b) Safe operation with no risks

c) Possible overheating with prolonged use

d) Voltage will automatically reduce

350 / 491

Category: Connection of all appliances (bulb, fan, socket, etc.) with the mains

350. (A) All electrical appliances are connected in parallel to the mains to ensure each appliance operates at its rated voltage.
(R) Parallel connection ensures that if one appliance fails, the others continue to operate independently.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

351 / 491

Category: Safety Precautions in Household Circuits

351. A water pump rated 1-5 kW, 220 V has a motor that draws a starting current of 10-4 A and a running current of 6-8 A. What should be the minimum current rating of the fuse used with this appliance?

a) Current rating equal to the running current (6-8 A)

b) Current rating just below the starting current (9 A)

c) Current rating slightly more than the starting current (10-5 A)

d) Current rating equal to the power rating (5 A)

352 / 491

Category: HOUSE WIRING (RING SYSTEM)

352. How are electrical appliances connected in the ring system wiring?

a) Series

b) Parallel

c) Series-Parallel

d) None of the above

353 / 491

Category: Earth Wire

353. Which of the following correctly describes the function of the earth wire symbol (\$) in a circuit diagram?

a) It represents the connection between the live and neutral wires.

b) It marks the location of the fuse in the circuit.

c) It indicates the grounding point for the metallic case of the appliance.

d) It denotes the power supply terminal for the appliance.

354 / 491

Category: Earthing (Grounding)

354. (A) The mixture of charcoal and salt around the copper plate in local earthing helps improve conductivity.
(R) Charcoal and salt create a damp environment, which enhances the flow of current to the earth.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

355 / 491

Category: Household Wiring (Ring System)

355. How are electrical appliances like bulbs and fans connected to the mains in household wiring?

a) In series with the mains

b) In parallel with the mains

c) Through a combination of series and parallel connections

d) Directly without any fuses or switches

356 / 491

Category: Dual Control Switch

356. (A) In a dual control switch setup, toggling either switch $S_1$ or $S_2$ reverses the state of the bulb (on to off or off to on).
(R) The dual control switch works by changing the connections between terminals $'a'$, $'b'$, and $'c'$ in such a way that each toggle alters the current path.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

357 / 491

Category: Connection of all appliances (bulb, fan, socket, etc.) with the mains

357. What happens if appliances are connected in series to the mains?

a) Each appliance gets 220 V

b) The total current increases

c) Each appliance gets less than 220 V

d) Only one appliance can be operated

358 / 491

Category: Energy Consumption

358. An electric bulb rated '220 V, 60 W' is connected to a 220 V mains supply. What is the resistance of its filament?

a) 400 \, \Omega

b) 600 \, \Omega

c) 806.67 \, \Omega

d) 1000 \, \Omega

359 / 491

Category: Main Fuse and Meter

359. What is the primary purpose of a fuse in an electrical circuit?

a) To increase the voltage in the circuit

b) To decrease the resistance in the circuit

c) To protect the circuit from excessive current

d) To provide extra power to appliances

360 / 491

Category: Practical Questions and Problems

360. (A) The earthing of an electric appliance is useful only if the fuse is placed in the live wire.
(R) If the fuse is placed in the neutral wire, the appliance may still remain electrically charged even after the fuse blows due to a fault.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

361 / 491

Category: Dual Control Switches and Staircase Wiring

361. (A) In a dual control switch setup, the bulb can be turned on or off from either end of the staircase regardless of the position of the other switch.
(R) The dual control switch works by changing the connection between terminals $ba$ and $bc$ to complete or break the circuit.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

362 / 491

Category: Power Distribution to a House

362. What is the primary purpose of the earth wire in house wiring?

a) To carry current from the source to the distribution board

b) To provide a return path for the current to the source

c) To connect all appliances in parallel

d) To provide safety by grounding leakage currents

363 / 491

Category: Types of Fuses

363. Which type of fuse is commonly used in appliances like refrigerators and air conditioners?

a) Knife blade fuse

b) Rewirable fuse

c) Cartridge type fuse

d) High rupture capacity fuse

364 / 491

Category: Fuse and Switch Locations

364. A geyser rated 4.4 kW, 220 V is connected to a circuit. What should be the minimum current rating of the fuse to be used in this circuit?

a) 10 A

b) 15 A

c) 20 A

d) 25 A

365 / 491

Category: Live Wire

365. In a correctly wired three-pin plug, where is the live wire connected and what would happen if it were incorrectly connected to the earth terminal?

a) Left pin (L); appliance won't work but is safe

b) Right pin (L); appliance casing may become dangerously live

c) Top pin (E); circuit protection remains effective

d) Any pin; modern plugs auto-correct the connection

366 / 491

Category: Three-Pin Plug and Socket

366. A metallic-bodied appliance with proper earthing develops an internal fault causing its live wire to touch the case. What sequence of events will occur when plugged into a properly wired socket?

a) The fuse blows after 5 minutes of continuous operation

b) Current flows momentarily through the user's body before the fuse blows

c) Appliance continues working normally with reduced efficiency

d) Heavy current flows to earth immediately blowing the fuse

367 / 491

Category: Dual Control Switch

367. A bulb controlled by dual switches $S_1$ and $S_2$ is currently on. The connection in $S_1$ is $‘bc’$ and in $S_2$ is $‘ba’$. Which operation will turn the bulb off?

a) Changing $S_1$ from $‘bc’$ to $‘ba’$

b) Changing $S_2$ from $‘ba’$ to $‘bc’$

c) Keeping both switches unchanged \interlinepenalty=10000

d) Reversing both switches simultaneously

368 / 491

Category: Household Wiring (Ring System)

368. In the ring system of household wiring, how does current reach an individual appliance?

a) Through a single path directly from the mains

b) Through two separate paths forming a ring

c) Only through the neutral wire

d) Through a series connection with other appliances

369 / 491

Category: Current Rating

369. A water pump rated at 2.2 kW, 220 V has a starting current of 12 A and a running current of 8 A. What should be the minimum current rating of the fuse to protect this pump?

a) 8 A

b) 10 A

c) 15 A

d) 20 A

370 / 491

Category: Power Distribution to a House

370. Where is the company fuse typically located in the power distribution to a house?

a) Inside the distribution box of the house

b) Near the main switch inside the house

c) At the sub-station

d) On the pole before connecting to the house meter

371 / 491

Category: Three-Pin Plug and Socket

371. What is the purpose of the top pin in a three-pin plug?

a) To supply power to the appliance

b) To connect the neutral wire

c) To provide a path for excess current to flow to the ground (earthing)

d) To increase the stability of the plug

372 / 491

Category: Dual Control Switches and Staircase Wiring

372. (A) Dual control switches are used to control a bulb from two different locations in staircase wiring.
(R) Dual control switches have three terminals 'a', 'b', and 'c' which allow changing connections between them to complete or break the circuit.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

373 / 491

Category: Proper Insulation

373. (A) High tension wires are made by twisting multiple thin insulated wires to increase surface area for better heat dissipation.
(R) The colour coding of wires ensures that high tension wires can handle higher current without overheating.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

374 / 491

Category: Reason for connecting the fuse in the live wire

374. Why is the fuse connected in the live wire of an electrical circuit?

a) To make the circuit look neat

b) Because it's cheaper to install in the live wire

c) To break the circuit before excessive current reaches the appliance

d) Because neutral wire can't carry current

375 / 491

Category: Three-Pin Plug and Socket

375. (A) The earth pin in a three-pin plug is made longer and thicker than the live and neutral pins.
(R) This ensures safety by making the earth connection first and prevents incorrect insertion into live or neutral holes.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

376 / 491

Category: Circuit Diagrams for Connecting Appliances

376. (A) In household wiring, all electrical appliances are connected in parallel to the mains.
(R) Parallel connection ensures that each appliance operates at its rated voltage and works independently of others.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

377 / 491

Category: HOUSE WIRING (RING SYSTEM)

377. What is the colour of the live wire in a house wiring ring system?

a) Black or Blue

b) Green or Yellow

c) Red or Brown

d) White or Grey

378 / 491

Category: Earthing (Grounding)

378. What happens if a faulty appliance with a metallic case is not earthed properly?

a) The appliance becomes more energy-efficient

b) The user may receive a fatal electric shock upon touching the appliance

c) The appliance automatically switches off

d) The fuse blows immediately

379 / 491

Category: Energy Consumption

379. In which unit does the electric meter measure household energy consumption?

a) Ampere (A)

b) Volt (V)

c) Watt (W)

d) Kilowatt-hour (kWh)

380 / 491

Category: The Role of Fuse in Household Circuits

380. What happens when the current flowing through a fuse wire exceeds its rated value?

a) The fuse wire becomes thicker

b) The fuse wire changes color but remains intact

c) The fuse wire melts and breaks the circuit

d) The fuse wire allows more current to pass safely

381 / 491

Category: Types of Fuses

381. (A) A rewirable fuse uses a porcelain holder to enclose the fuse wire.
(R) The porcelain holder provides electrical insulation and prevents short circuits.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

382 / 491

Category: Neutral Wire

382. What is the color code for the neutral wire in house wiring?

a) Green

b) Red

c) Blue

d) Yellow

383 / 491

Category: Earthing (Grounding)

383. What is the significance of color coding in the wires of a three-core flexible cable used in appliances?

a) It indicates the voltage rating of the appliance.

b) It helps in distinguishing between high-power and low-power appliances.

c) It ensures aesthetic appeal of the wiring system.

d) It provides resistance against wear and tear.

384 / 491

Category: Dual Control Switches and Staircase Wiring

384. Why should a switch not be touched with wet hands?

a) It can damage the switch

b) Water improves conductivity, increasing safety

c) Wet hands make the switch slippery

385 / 491

Category: Fuse and Switch Locations

385. (A) A fuse is always connected in the live wire to protect the appliance from excessive current.
(R) Connecting the fuse in the neutral wire keeps the appliance at a high potential when the fuse blows, risking electric shock.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

386 / 491

Category: Earth Wire

386. A thick copper plate (50 cm x 50 cm) is buried in the ground for local earthing. Why is this plate surrounded by a mixture of charcoal and salt?

a) To reduce the cost of the earthing setup.

b) To increase the aesthetic appearance of the earthing pit.

c) To prevent corrosion of the copper plate.

d) To enhance the conductivity and ensure good contact with the earth.

387 / 491

Category: Parallel Circuits:

387. (A) In a household wiring system, all electrical appliances are connected in parallel to ensure they operate at the rated voltage.
(R) Parallel connection ensures that each appliance receives the full voltage from the mains and operates independently of others.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

388 / 491

Category: Practical Questions and Problems

388. A three-pin plug is used to connect an electric appliance to the mains. The top pin is thicker and longer than the other two pins. What is the primary reason for this design feature?

a) To make the plug more durable and resistant to wear.

b) To ensure the earth connection is established first and broken last.

c) To prevent the plug from being inserted upside down.

d) To reduce resistance in the connection.

389 / 491

Category: HOUSE WIRING (RING SYSTEM)

389. (A) In the ring system, if a fuse burns in one appliance, it does not affect other appliances connected in parallel.
(R) Each appliance in the ring system has a separate fuse and switch, ensuring independent operation.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

390 / 491

Category: Earthing (Grounding)

390. Why is it necessary to remove paint from the metallic case of an appliance before making an earth connection?

a) Paint increases conductivity, enhancing earthing efficiency.

b) Paint provides additional insulation, reducing electric shock risk.

c) Paint helps in identifying the correct earthing point.

d) Paint makes the appliance rust-resistant, improving longevity.

391 / 491

Category: Power Generation

391. (A) The voltage generated at power stations is stepped up to 132 kV for transmission to reduce energy losses.
(R) Power loss in transmission lines is proportional to the square of the current, and stepping up voltage reduces the current for a given power.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

392 / 491

Category: Current Rating

392. The current rating of a fuse is 5 A. What does this statement mean?

a) It means the fuse can only carry a minimum current of 5 A.

b) It means the fuse will blow if the current is less than 5 A.

c) It means the fuse is designed to carry up to 5 A safely and will blow if exceeded.

d) It means the fuse will only work for appliances rated exactly 5 A.

393 / 491

Category: Earth Wire

393. (A) Earthing of an electrical appliance with a metallic case is essential for safety.
(R) If the live wire comes in contact with the metallic case, earthing ensures the current flows to the ground, blowing the fuse and preventing electric shock.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

394 / 491

Category: FUSE

394. How is the current rating of a fuse related to its thickness?

a) Directly proportional

b) Inversely proportional

c) No relation

d) Exponential relation

395 / 491

Category: Current Rating

395. A household has a main MCB rated at 16 A. It powers a refrigerator (300 W), an air conditioner (1.5 kW), and 5 LED bulbs (10 W each). If all appliances operate simultaneously at 220 V, what percentage of the MCB's capacity is utilized?

a) 32\%

b) 48\%

c) 53\%

d) 67\%

396 / 491

Category: Disadvantages of connecting the appliances in series

396. Why can't household appliances operate independently when connected in series?

a) Because they share the same current

b) Because switching one off affects all others

c) Because their voltages add up

d) Because their power ratings change

397 / 491

Category: Dual Control Switch

397. In a dual control switch setup, if the bulb is off when both switches are in the $‘ba’$ position, what happens if you toggle $S_1$ first and then $S_2$ immediately afterward?

a) Bulb remains off

b) Bulb turns on and stays on

c) Bulb turns on then off

d) Bulb flickers continuously

398 / 491

Category: Earthing (Grounding)

398. (A) The presence of charcoal and salt mixture in local earthing reduces the contact resistance between the copper plate and the ground.
(R) Charcoal and salt increase the conductivity of the surrounding soil, ensuring a low-resistance path for fault currents to dissipate into the earth.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

399 / 491

Category: Practical Questions and Problems

399. (A) The metallic case of an electric appliance is connected to the earth wire for safety.
(R) Earthing prevents electric shock by providing a low-resistance path for leakage current.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

400 / 491

Category: Earth Wire

400. What is the standard insulation color of the earth wire in a three-core flexible cable?

a) Red

b) Black

c) Green

d) Blue

401 / 491

Category: HOUSE WIRING (RING SYSTEM)

401. In the ring system of house wiring, why is the main wire's current-carrying capacity lower than that required for a direct connection to the mains?

a) The ring system uses thicker wires, which inherently reduce resistance.

b) Each appliance draws less current due to parallel connections.

c) Current splits into two paths, reducing the effective load on the main wire.

d) The distribution box regulates the current flow efficiently.

402 / 491

Category: SAFETY PRECAUTIONS WHILE USING THE ELECTRICITY

402. Why is local earthing important in household electrical systems?

a) It reduces electricity bills

b) It prevents overcharging of batteries

c) It ensures excessive current flows to the ground, preventing fires and shocks

d) It increases the voltage supply to appliances

403 / 491

Category: Appliance Earthing

403. What happens if the metallic case of an appliance is not earthed and the live wire comes in contact with it due to insulation failure?

a) The appliance will stop working immediately

b) The fuse will blow off even without earthing

c) The person touching the appliance may receive a severe electric shock

d) The appliance will continue to function normally

404 / 491

Category: Avoid Wet Hands:

404. What precaution should be taken while operating a switch to prevent electric shock?

a) Always use gloves \b�on dry hands only

b) Wear rubber shoes

c) Use a wooden stick

405 / 491

Category: Avoid Wet Hands:

405. Why is it dangerous to connect a switch in the neutral wire of an electrical circuit?

a) It prevents the appliance from turning off completely

b) It causes excessive heating of the switch contacts

c) It increases resistance in the circuit

406 / 491

Category: Earth Wire

406. What is the colour code for the earth wire in electrical circuits?

a) Red

b) Blue

c) Green

d) Yellow

407 / 491

Category: Choosing the Correct Fuse

407. A household circuit has a main fuse rated at 10 A. The following appliances are running simultaneously: a 1.5 kW air conditioner, two 100 W ceiling fans, and five 60 W bulbs. What is the maximum number of additional 100 W bulbs that can be safely added without exceeding the fuse's capacity, given the mains voltage is 220 V?

a) 1

b) 2

c) 3

d) 4

408 / 491

Category: Main Fuse and Meter

408. (A) The main fuse is connected in the live wire to protect the circuit from overloading and short circuiting.
(R) The main fuse melts when the current exceeds its rating, breaking the circuit and preventing damage to appliances.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

409 / 491

Category: Avoid Wet Hands:

409. Why should you avoid touching electrical appliances with wet hands?

a) It increases the risk of slipping

b) It can cause rusting of the appliance

c) It forms a conducting path for electric current

d) It makes the appliance heavier

410 / 491

Category: Advantages of connecting the appliances in parallel

410. If three lamps are connected in a household circuit, what would be the consequence if one lamp burns out when connected in parallel versus in series?

a) Both parallel and series circuits will turn off all lamps if one fails

b) Only the parallel circuit keeps the other lamps lit if one fails

c) The series circuit keeps the other lamps lit at reduced brightness

d) Parallel and series circuits behave identically in this scenario

411 / 491

Category: CIRCUITS WITH DUAL CONTROL SWITCHES (STAIRCASE WIRING)

411. Which of the following is the most critical safety precaution when using dual control switches?

a) Ensuring the switches are made of plastic

b) Using switches only during the day \button Never touching the switch with wet hands \button Keeping the switches covered at all times

412 / 491

Category: Types of Fuses

412. Where should a fuse be connected in an electrical circuit to ensure safety?

a) In the neutral wire after the appliance

b) In the earth wire

c) In the live wire before the appliance

d) Both live and neutral wires

413 / 491

Category: Appliance Earthing

413. (A) The earth pin in a three-pin plug is longer and thicker than the live and neutral pins.
(R) The earth pin is designed to ensure safety by making the earth connection first and preventing accidental insertion into live or neutral holes.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

414 / 491

Category: Current Rating

414. An electric kettle is rated 3 kW, 250 V. Can this kettle be used in a circuit containing a fuse of current rating 13 A?

a) No, because the kettle requires 15 A

b) Yes, because the kettle's current (12 A) is within the fuse's limit (13 A)

c) No, because the voltage is too high

d) Yes, because 3 kW is safe for any fuse

415 / 491

Category: Live Wire

415. What is the standard color coding for the live wire in household electrical wiring?

a) Green with yellow stripes

b) Black or light blue

c) Red or brown

d) Yellow or white

416 / 491

Category: Current Rating

416. (A) A fuse with a current rating of 15 A is used for an air conditioner rated 3.3 kW at 220 V.
(R) The current drawn by the air conditioner is calculated as $I = \frac{P}{V} = \frac{3300}{220} = 15$ A, which matches the fuse rating.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

417 / 491

Category: Power Distribution to a House

417. Which of the following is an advantage of the ring system of house wiring?

a) It uses thicker wires to reduce resistance

b) Current can flow through a single fixed path only

c) Current can reach an appliance through two separate paths

d) It eliminates the need for fuses in the circuit

418 / 491

Category: Earthing (Grounding)

418. Which of the following materials is mixed with charcoal around the copper plate in local earthing to improve conductivity?

a) Sand

b) Gravel

c) Cement

d) Salt

419 / 491

Category: Live Wire

419. A household circuit has a fuse connected in series with the live wire. If a high-power appliance is switched on, causing excessive current flow, which of the following will happen and why?

a) The neutral wire will break first since it carries return current

b) The fuse will melt and break the circuit to prevent hazards

c) The earth wire will divert excess current to the ground

d) The switch will automatically trip without any physical damage

420 / 491

Category: Neutral Wire

420. A household electric circuit has the switch connected to the neutral wire instead of the live wire. What is the potential danger of this setup?

a) The appliance will not work even when the switch is on.

b) The appliance remains at high potential when the switch is off, posing a shock hazard.

c) The circuit breaker will trip frequently.

d) The neutral wire will overheat due to excessive current flow.

421 / 491

Category: CIRCUITS WITH DUAL CONTROL SWITCHES (STAIRCASE WIRING)

421. When switch $S_1$ in a staircase circuit changes its position from 'ba' to 'bc', what happens to the bulb?

a) Bulb turns OFF

b) Bulb turns ON

c) Bulb flickers

d) Bulb remains unaffected

422 / 491

Category: Three-Pin Plug and Socket

422. (A) The earth pin in a three-pin plug is thicker and longer than the live and neutral pins.
(R) The earth pin is made longer to ensure the earth connection is established first, and thicker to prevent its insertion into the live or neutral socket holes.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

423 / 491

Category: Three-Pin Plug and Socket

423. An electrician needs to replace a damaged high tension wire in an industrial setup. Which of these characteristics MUST the new wire possess to be suitable?

a) Single solid copper core with plastic coating

b) Multiple thin insulated strands twisted together

c) Aluminum foil wrapped around rubber insulation

d) Coated with conductive paint for better grounding

424 / 491

Category: HOUSE WIRING (RING SYSTEM)

424. (A) In the ring system of house wiring, each appliance can receive current through two separate paths.
(R) This is because the wires form a loop, allowing current to flow in both directions to reach any point in the circuit.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

425 / 491

Category: Earth Wire

425. In a household electrical circuit, the live wire accidentally comes into contact with the metallic case of an appliance due to insulation failure. The appliance is properly earthed, and local earthing is present near the kWh meter. What happens when a person touches the metallic case?

a) The person receives a severe electric shock because the current passes through their body.

b) The fuse blows, but the person still gets a mild shock.

c) No current flows through the earth wire, and the person receives a shock.

d) The fuse blows immediately, and the person remains unharmed.

426 / 491

Category: Main Fuse and Meter

426. (A) The main fuse is connected in the live wire after the kWh meter to protect the circuit from overloading.
(R) The fuse wire melts when the current exceeds its rated capacity due to the heating effect of current.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

427 / 491

Category: FUSE

427. For a fuse wire with specific resistance $\rho$, current $I = 4$ A, radius $r = 0.3$ mm, and surrounding temperature $T = 300$ K, if Stefan's constant $\sigma = 5.67 \times 10^{-8}$ W/m$^2$K$^4$, what is the rise in temperature $\Delta T$?

a) 5.5 K

b) 11.3 K

c) 22.6 K

d) 45.2 K

428 / 491

Category: Earthing (Grounding)

428. (A) The thickness of the earth pin in a three-pin plug is greater than the live and neutral pins to ensure it makes contact first when inserted into the socket.
(R) A thicker and longer earth pin ensures reliable earthing connection before the live wire becomes active, preventing electric shock hazards.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

429 / 491

Category: Appliance Earthing

429. In a three-core flexible cable used for electrical appliances, which colour is used for the earth wire?

a) Red (or brown)

b) Black (or light blue)

c) Green

d) Yellow

430 / 491

Category: Dual Control Switch

430. What happens when the knob of a dual control switch is shifted to the right?

a) Terminal 'b' connects to terminal 'a'

b) Terminal 'b' connects to terminal 'c'

c) The circuit breaks completely

d) The switch gets damaged

431 / 491

Category: Power Generation

431. At what voltage and frequency is electric power generated at the power generating station?

a) $220 \text{ V}, 50 \text{ Hz}$

b) $11 \text{ kV}, 60 \text{ Hz}$

c) $11 \text{ kV}, 50 \text{ Hz}$

d) $132 \text{ kV}, 50 \text{ Hz}$

432 / 491

Category: Types of Fuses

432. In a cartridge type fuse with a glass tube enclosure, if the current rating of the fuse is doubled, what would be the impact on the thickness of the fuse wire assuming the same material is used?

a) Thickness remains the same

b) Thickness decreases by half

c) Thickness approximately doubles

d) Thickness increases by $\sqrt{2}$ times

433 / 491

Category: COLOUR CODING OF WIRES IN A CABLE

433. (A) The earth wire in a three-pin plug is colored green.
(R) The green color coding ensures the earth connection is made first for safety.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

434 / 491

Category: FUSE

434. A fuse wire works based on which principle?

a) Heating effect of current

b) Magnetic effect of current

c) Chemical effect of current

d) Electromagnetic induction

435 / 491

Category: Dual Control Switch

435. Consider a dual control switch system used in a staircase with switches $S_1$ and $S_2$. If the bulb is initially off with connection $‘ba’$ in $S_1$ and $‘bc’$ in $S_2$, which of the following actions will turn the bulb on?

a) Shifting $S_1$ from $‘ba’$ to $‘bc’$

b) Shifting $S_2$ from $‘bc’$ to $‘ba’$

c) Keeping both switches unchanged

d) Shifting both switches simultaneously

436 / 491

Category: Earthing (Grounding)

436. (A) Earthing the metallic case of an appliance prevents electric shock to the user.
(R) The earth wire provides a low-resistance path for the current to flow to the ground, causing the fuse to blow in case of a fault.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

437 / 491

Category: Safety through Earthing

437. What is the purpose of mixing charcoal and salt around the copper plate in local earthing?

a) To make the copper plate more durable

b) To prevent corrosion of the copper plate

c) To provide insulation to the plate

d) To improve conductivity between the plate and the ground

438 / 491

Category: Parallel Circuits:

438. (A) Two identical bulbs rated 220 V, 60 W connected in parallel will consume the same total power as a single bulb of 120 W rating at 220 V.
(R) In parallel connection, the voltage across each bulb remains the same as the supply voltage, ensuring each bulb operates at its rated power.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

439 / 491

Category: Proper Insulation

439. (A) The insulation of wires should be checked periodically to prevent electric shocks.
(R) Over time, the insulation on wires becomes brittle and cracks off, exposing the live wire.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

440 / 491

Category: Energy Consumption

440. An electric bulb rated '220 V, 100 W' and another bulb rated '220 V, 60 W' are connected in series across a 220 V mains supply. What is the total power consumed by this combination?

a) 22.5 W

b) 37.5 W

c) 160 W

d) 27.3 W

441 / 491

Category: Function of Fuse

441. (A) A fuse wire with a higher current rating is thicker than one with a lower current rating because the rise in temperature of the fuse wire depends inversely on the cube of its radius.
(R) The rise in temperature of a fuse wire is directly proportional to the square of the current passing through it and inversely proportional to the cube of its radius.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

442 / 491

Category: Energy Consumption

442. A fuse wire of length $l$, radius $r$, and specific resistance $\rho$ has resistance $R$. If the current exceeds its rating, the fuse melts due to heat. What is the expression for the heat produced per second in the fuse wire when current $I$ flows through it?

a) $H = \frac{I \rho l}{\pi r^2}$

b) $H = \frac{I^2 \rho l}{\pi r^2}$

c) $H = \frac{I \rho l^2}{\pi r^2}$

d) $H = \frac{I^2 \rho}{\pi r l}$

443 / 491

Category: Safety through Earthing

443. What is the purpose of surrounding the copper plate in local earthing with charcoal and salt mixture?

a) To prevent corrosion of the copper plate

b) To improve the conductivity between the plate and the ground

c) To increase the lifespan of the earthing system

d) To insulate the copper plate from the ground

444 / 491

Category: Connection of all appliances (bulb, fan, socket, etc.) with the mains

444. Why is independent operation possible when appliances are connected in parallel?

a) Because they share the same current \bBecause they share the same voltage

b) Because each has a separate circuit path

c) Because the fuse blows when one is turned off

445 / 491

Category: Reason for connecting the fuse in the live wire

445. (A) The fuse is always connected in the live wire to protect electrical appliances from excessive current.
(R) Connecting the fuse in the live wire ensures that the circuit breaks before the current reaches the appliance, preventing any potential electric shock when touching a faulty appliance.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

446 / 491

Category: Main Fuse and Meter

446. A household has appliances with total power ratings of 2 kW (lights and fans), 3 kW (geyser), and 1.5 kW (refrigerator). If the supply voltage is 220 V, what should be the minimum current rating of the main fuse for safe operation?

a) 20 A

b) 25 A

c) 30 A

d) 35 A

447 / 491

Category: Connection of all appliances (bulb, fan, socket, etc.) with the mains

447. (A) All household appliances like bulbs, fans, and sockets are connected in parallel to the mains supply.
(R) Parallel connection ensures that each appliance operates at its rated voltage and works independently of others.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

448 / 491

Category: Safety through Earthing

448. What is the reason for making the earth pin in a three-pin plug thicker and longer than the other two pins?

a) To make the plug look different

b) To save manufacturing costs

c) To reduce resistance in the earth connection

d) To ensure safety by making earth contact first and preventing wrong insertion

449 / 491

Category: Power Distribution to a House

449. A household receives power at $220 V$ with a main fuse rated at $30 A$. What is the maximum total power that can be safely drawn by all appliances in the house without tripping the main fuse?

a) 2200 W

b) 4400 W

c) 6600 W

d) 8800 W

450 / 491

Category: CIRCUITS WITH DUAL CONTROL SWITCHES (STAIRCASE WIRING)

450. (A) In a staircase wiring setup, the bulb can be turned on/off from either switch $S_1$ or $S_2$.
(R) The dual control switch changes connections between terminals 'ba' and 'bc' to complete or break the circuit.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

451 / 491

Category: Fuse and Switch Locations

451. Why should a switch always be connected in the live wire?

a) To allow current flow in both directions

b) Because the neutral wire cannot carry current

c) To disconnect the appliance from the high potential point when off

d) To increase the voltage across the appliance

452 / 491

Category: Disadvantages of connecting the appliances in series

452. Three appliances with resistances 2Ω, 4Ω and 6Ω are connected in series to a 120V source. What will be the voltage across the 4Ω appliance?

a) 20V

b) 30V

c) 40V

d) 60V

453 / 491

Category: The Role of Fuse in Household Circuits

453. Which property makes lead-tin alloy suitable for fuse wires?

a) High conductivity and high melting point

b) Low melting point and high resistance

c) High tensile strength and durability

d) Insulating properties

454 / 491

Category: Types of Fuses

454. What material is commonly used for making fuse wires due to its low melting point?

a) Copper

b) Aluminium

c) Alloy of lead and tin

d) Silver

455 / 491

Category: Live Wire

455. (A) The live wire should always be connected to the switch and fuse in an electrical circuit.
(R) The live wire carries high potential current from the source to the appliance, and connecting it to the switch and fuse ensures safety by allowing the circuit to be turned off or disconnected during faults.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

456 / 491

Category: Disadvantages of connecting the appliances in series

456. If two identical bulbs are connected in series, what happens to the current when a third identical bulb is added in series?

a) Current remains same

b) Current increases

c) Current decreases

d) Current becomes zero

457 / 491

Category: Step-Up and Step-Down Transformers

457. Where is a step-down transformer typically used in the power distribution system?

a) At power generating stations to step up voltage

b) Between two high-voltage transmission lines

c) At city sub-stations to reduce voltage for domestic use

d) In generating electricity from solar panels

458 / 491

Category: Circuit Diagrams for Connecting Appliances

458. Why are household appliances connected in parallel to the mains supply?

a) Each appliance operates at a lower voltage than its rated voltage.

b) All appliances must be turned on or off simultaneously.

c) Appliances receive equal current regardless of their power rating.

d) Each appliance gets full voltage and operates independently.

459 / 491

Category: Parallel Circuits:

459. Two identical bulbs rated 220 V, 60 W are connected in parallel. What is the total power consumed by the circuit?

a) 30 W

b) 60 W

c) 90 W

d) 120 W

460 / 491

Category: Disadvantages of connecting the appliances in series

460. A circuit has three appliances of resistances 10Ω, 20Ω, and 30Ω connected in series to a 120V source. What happens to the power consumed by the 20Ω appliance if a fourth appliance of 40Ω is added to the circuit?

a) The power increases to 96W

b) The power decreases to 28.8W

c) The power remains the same at 80W

d) The power becomes zero

461 / 491

Category: Practical Questions and Problems

461. In a three-pin plug, to which wire should the fuse be connected?

a) Neutral wire

b) Earth wire

c) Live wire

d) Both live and neutral wires

462 / 491

Category: SAFETY PRECAUTIONS WHILE USING THE ELECTRICITY

462. An electric kettle with a metal body is frequently used in a kitchen. Which combination of safety measures will best prevent electric shock?

a) Wet hands operation and no earthing

b) Periodic insulation checks and earthing

c) No fuse and local earthing

d) Frequent use without maintenance

463 / 491

Category: Energy Consumption

463. (A) When two identical bulbs rated 220 V, 60 W are connected in series across 220 V mains, the total power consumed is less than when they are connected in parallel.
(R) In a series connection, the voltage across each bulb is halved, reducing the power consumed per bulb to one-fourth of its rated value.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

464 / 491

Category: TRANSMISSION OF POWER FROM THE GENERATING STATION TO THE CONSUMER

464. (A) Electric power is transmitted at high voltages (132 kV) to reduce energy loss in transmission lines.
(R) Power loss in transmission lines is given by $I^2Rt$, and higher voltage reduces the current for a given power.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

465 / 491

Category: HOUSE WIRING (RING SYSTEM)

465. Three identical bulbs rated 220 V, 100 W are connected in series across 660 V mains in a faulty wiring setup. What percentage of their rated power will each bulb deliver?

a) 11.1\%

b) 33.3\%

c) 66.7\%

d) 100\%

466 / 491

Category: Practical Questions and Problems

466. What is the color code for the insulation on the live wire?

a) Blue

b) Green

c) Brown

d) Yellow

467 / 491

Category: COLOUR CODING OF WIRES IN A CABLE

467. Where should the switch be connected in an electrical circuit?

a) Live wire

b) Neutral wire

c) Earth wire

d) Any wire

468 / 491

Category: Energy Consumption

468. Two identical bulbs rated '220 V, 60 W' are connected in series across a 220 V mains. What is the total power consumed by both bulbs?

a) 30 \, W

b) 60 \, W

c) 120 \, W

d) 240 \, W

469 / 491

Category: Power Generation

469. Why is high voltage used for transmitting electric power over long distances?

a) To increase the speed of electricity

b) To decrease the current and reduce energy losses

c) To make the power supply more consistent

d) To prevent voltage fluctuations

470 / 491

Category: Working Mechanism

470. Which of these is an example of a simple working mechanism?

a) A computer program

b) A lever used to lift heavy objects

c) A complex chemical reaction

d) A philosophical theory

471 / 491

Category: Types of Fuses

471. (A) A rewirable fuse is commonly used in household wiring because it has a low melting point alloy wire.
(R) The fuse wire in rewirable fuses is made of an alloy of lead and tin to ensure it melts when current exceeds the rated value.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

472 / 491

Category: Parallel Circuits:

472. A household circuit has two appliances connected in parallel: a heater rated 220 V, 1000 W and a lamp rated 220 V, 40 W. What is the approximate equivalent resistance of this parallel combination when both appliances are operational?

a) 45.6 $\Omega$

b) 48.3 $\Omega$

c) 50.8 $\Omega$

d) 52.1 $\Omega$

473 / 491

Category: Proper Insulation

473. What material is commonly used for fuse wires due to its low melting point?

a) Copper

b) Aluminium

c) Lead-tin alloy

d) Silver

474 / 491

Category: Reason for connecting the fuse in the live wire

474. If a fuse is connected in the neutral wire of a circuit and there is excessive current, what happens when a person touches the faulty appliance?

a) The appliance stops working but no shock occurs

b) The person receives an electric shock due to connection with the live wire

c) The fuse melts and breaks the circuit completely

d) The appliance continues to function normally

475 / 491

Category: Practical Questions and Problems

475. What is the purpose of the top pin in a three-pin plug being thicker and longer than the other two?

a) To make the plug look symmetrical.

b) To ensure the earth connection is made first and broken last for safety.

c) To reduce the cost of manufacturing.

d) To prevent the plug from overheating.

476 / 491

Category: Parallel Circuits:

476. Two identical bulbs are connected first in series and then in parallel across the same voltage source. Which statement is correct about their brightness and power consumption?

a) Bulbs in series are brighter and consume more power.

b) Bulbs in parallel are brighter and consume less power.

c) Bulbs in series are dimmer and consume less power.

d) Bulbs in parallel are brighter and consume more power.

477 / 491

Category: Safety Precautions in Household Circuits

477. Why is an MCB considered safer than a traditional fuse in household circuits?

a) MCBs have colorful switches

b) MCBs respond slower than fuses

c) MCBs require frequent replacement

d) MCBs respond faster and can be reset

478 / 491

Category: Disadvantages of connecting the appliances in series

478. (A) If three identical bulbs rated at 220V are connected in series to a 660V source, each bulb will glow with its full brightness.
(R) The voltage across each appliance in a series connection is equal to the total applied voltage divided by the number of appliances.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

479 / 491

Category: The Role of Fuse in Household Circuits

479. Why is an alloy of lead and tin used for making fuse wires?

a) It has high conductivity and low melting point.

b) It has high melting point and low resistance.

c) It has low melting point and high resistance.

d) It is cheap and easily available.

480 / 491

Category: Step-Up and Step-Down Transformers

480. (A) A step-up transformer at a generating station increases the transmission voltage to reduce energy losses, as power loss in transmission lines is given by $P = I^2 R$.
(R) Higher transmission voltage reduces the current for a given power ($I = \frac{P}{V}$), thus minimizing energy loss.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

481 / 491

Category: Dual Control Switch

481. (A) A dual control switch allows controlling a single appliance from two different locations.
(R) This is because the dual control switch has three terminals, and changing the knob position changes the connections between these terminals to complete or break the circuit.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

482 / 491

Category: FUSE

482. What is the preferred property of the material used for a fuse wire?

a) High melting point

b) Low melting point

c) High conductivity

d) High durability

483 / 491

Category: SAFETY PRECAUTIONS WHILE USING THE ELECTRICITY

483. (A) Using wires with current carrying capacity higher than the total current in the circuit prevents overheating and fire hazards.
(R) Overheating of wires occurs when the current exceeds their carrying capacity, leading to insulation breakage or short circuits.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

484 / 491

Category: Reason for connecting the fuse in the live wire

484. Why is it unsafe to connect a fuse in the neutral wire of an electrical circuit?

a) The appliance will immediately explode when the fuse blows

b) It causes voltage fluctuations in the main supply line

c) The circuit cannot be completed if the fuse blows

d) The appliance remains connected to high potential even after the fuse blows

485 / 491

Category: Reason for connecting the fuse in the live wire

485. (A) The fuse must be connected in the live wire to ensure safety.
(R) Connecting the fuse in the neutral wire leaves the appliance connected to the high potential live wire, posing a risk of electric shock.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

486 / 491

Category: Choosing the Correct Fuse

486. If the radius of a fuse wire is doubled while keeping the current rating constant, how does the temperature rise in the wire change?

a) Increases by a factor of 2

b) Decreases by a factor of 2

c) Decreases by a factor of 8

d) Remains unchanged

487 / 491

Category: Types of Fuses

487. (A) A fuse wire made of copper is suitable for protecting appliances due to its high melting point.
(R) The temperature rise in a fuse wire is inversely proportional to the cube of its radius and directly proportional to the square of the current passing through it.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

488 / 491

Category: Three-Pin Plug and Socket

488. (A) The earth pin in a three-pin plug is longer and thicker than the live and neutral pins.
(R) This ensures safety by making the earth connection first and preventing incorrect insertion into live or neutral holes.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

489 / 491

Category: Dual Control Switches and Staircase Wiring

489. Which action completes the circuit in dual control switch staircase wiring when initially bulb is off?

a) Changing both switches simultaneously

b) Changing any one switch's connection

c) Reversing both switches' connections

d) Keeping both switches unchanged

490 / 491

Category: Proper Insulation

490. What is the colour code for the live wire in a power circuit cable?

a) Red

b) Blue

c) Brown

d) Green

491 / 491

Category: Disadvantages of connecting the appliances in series

491. (A) Connecting appliances in series reduces their operating voltage, so they do not function efficiently.
(R) The total voltage divides across each appliance connected in series based on their resistances.

a) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

b) Both Assertion and Reason are true, but Reason is NOT the correct explanation of Assertion.

c) Assertion is true, but Reason is false.

d) Assertion is false, but Reason is true.

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