JAMB and WAEC Physics questions: Electrical energy and power

24 questions with answers and explanations. Tap an option to check yourself.

1. Question 1· Electrical energy and power· JAMB

   A 1.5 kW heater is used for 4 hours. If electricity costs ₦50 per kWh, find the cost.

   • A₦300
   • B₦75
   • C₦200
   • D₦6

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   Explanation and discussion

2. Question 2· Electrical energy and power· WAEC

   The fuse rating for a 920 W appliance on a 230 V supply should be about

   • A13 A
   • B1 A
   • C5 A
   • D30 A

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   Explanation and discussion

3. Question 3· Electrical energy and power· JAMB

   How many kilowatt-hours of energy does a 100 W bulb use in 10 hours?

   • A10 kWh
   • B1 kWh
   • C1000 kWh
   • D0.1 kWh

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   Explanation and discussion

4. Question 4· Electrical energy and power· JAMB

   A 13 A fuse is fitted in a 240 V circuit. What is the maximum power it allows?

   • A3,120 W
   • B18.5 W
   • C253 W
   • D31,200 W

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   Explanation and discussion

5. Question 5· Electrical energy and power· WAEC

   Find the resistance of a lamp rated 100 W, 240 V.

   • A2.4 Ω
   • B576 Ω
   • C24 000 Ω
   • D0.42 Ω

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   Explanation and discussion

6. Question 6· Electrical energy and power· JAMB

   A 12 V supply is connected across a 6 Ω resistor. Find the power.

   • A72 W
   • B24 W
   • C2 W
   • D0.5 W

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   Explanation and discussion

7. Question 7· Electrical energy and power· JAMB

   In a household plug, the fuse should be connected in the

   • Ainsulation
   • Bneutral wire
   • Cearth wire
   • Dlive wire

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   Explanation and discussion

8. Question 8· Electrical energy and power· JAMB

   An electric heater rated 2 kW is used for 3 hours. The energy consumed is:

   • A6 kWh
   • B1.5 kWh
   • C0.67 kWh
   • D5 kWh

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   Explanation and discussion

9. Question 9· Electrical energy and power· JAMB

   A current of 2 A flows through a 5 Ω resistor for 10 s. Find the heat produced.

   • A100 J
   • B200 J
   • C20 J
   • D50 J

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   Explanation and discussion

10. Question 10· Electrical energy and power· WAEC

    A fuse protects a circuit by

    • Aincreasing the voltage
    • Bstoring extra current
    • Cmelting when the current is too large
    • Dearthing the appliance

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    Explanation and discussion

11. Question 11· Electrical energy and power· WAEC

    A 2 kW heater is used for 3 hours. The energy used is

    • A0.67 kWh
    • B1.5 kWh
    • C5 kWh
    • D6 kWh

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    Explanation and discussion

12. Question 12· Electrical energy and power· JAMB

    A 60 W bulb is used on a 240 V supply. Find the current it draws.

    • A4 A
    • B0.25 A
    • C14 400 A
    • D0.5 A

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    Explanation and discussion

13. Question 13· Electrical energy and power· WAEC

    A kettle is rated 960 W, 240 V. Find its resistance.

    • A230,400 Ω
    • B4 Ω
    • C0.25 Ω
    • D60 Ω

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    Explanation and discussion

14. Question 14· Electrical energy and power· JAMB

    Find the resistance of a bulb rated 100 W, 220 V.

    • A0.45 Ω
    • B2.2 Ω
    • C484 Ω
    • D22 000 Ω

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    Explanation and discussion

15. Question 15· Electrical energy and power· WAEC

    If electricity costs ₦50 per kWh, running a 100 W bulb for 10 hours costs

    • A₦50
    • B₦500
    • C₦5
    • D₦5,000

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    Explanation and discussion

16. Question 16· Electrical energy and power· WAEC

    A 500 W electric iron is used for 4 hours. At ₦80 per kWh, find the cost.

    • A₦40
    • B₦1,600
    • C₦16
    • D₦160

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    Explanation and discussion

17. Question 17· Electrical energy and power· WAEC

    An electric iron rated 1,000 W is used for 2 hours. The energy used, in kilowatt-hours, is

    • A500 kWh
    • B2,000 kWh
    • C0.5 kWh
    • D2 kWh

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    Explanation and discussion

18. Question 18· Electrical energy and power· JAMB

    A 2 kW heater is used for 3 hours. How much energy does it use?

    • A0.67 kWh
    • B6 kWh
    • C1.5 kWh
    • D6,000 kWh

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    Explanation and discussion

19. Question 19· Electrical energy and power· WAEC

    A heater draws 5 A from a 220 V supply. Find its power.

    • A225 W
    • B44 W
    • C1100 W
    • D4400 W

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    Explanation and discussion

20. Question 20· Electrical energy and power· WAEC

    The fuse in a three-pin plug is connected in the

    • Aearth wire
    • Bneutral wire
    • Cany of the wires
    • Dlive wire

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    Explanation and discussion