WAEC Physics questions: Electrical energy and power

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

1. Question 1· 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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2. Question 2· 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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3. Question 3· 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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4. Question 4· 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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5. Question 5· 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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6. Question 6· 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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7. Question 7· 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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8. Question 8· 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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9. Question 9· 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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10. Question 10· 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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11. Question 11· Electrical energy and power· WAEC

    A 60 W bulb is used for 5 hours a day for 30 days. At ₦50 per kWh, what is the cost?

    • A₦4,500
    • B₦9,000
    • C₦15
    • D₦450

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    Explanation and discussion