WAEC Physics questions

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

1. Question 81· 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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2. Question 82· 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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3. Question 83· 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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4. Question 84· 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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5. Question 85· 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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6. Question 86· 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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7. Question 87· Electromagnetic induction· WAEC

   The iron core of a transformer is laminated in order to reduce

   • Aeddy current losses
   • Bthe resistance of the coils
   • Cthe flux linkage
   • Dthe output voltage

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8. Question 88· Electromagnetic induction· WAEC

   When a magnet's north pole is pushed into a coil, the induced current makes the near end of the coil a north pole. This illustrates

   • ALenz's law
   • BCoulomb's law
   • COhm's law
   • DNewton's first law

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9. Question 89· Electromagnetic induction· WAEC

   Transformers do not work with direct current because

   • Ad.c. does not produce a changing magnetic field
   • Bd.c. is too strong
   • Cd.c. has no voltage
   • Dthe core melts

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10. Question 90· Electromagnetic induction· WAEC

    A transformer has 100 turns in the primary and 500 in the secondary. With 240 V input, the output is

    • A48 V
    • B1,200 V
    • C240 V
    • D600 V

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11. Question 91· Electromagnetic induction· WAEC

    The device that changes mechanical energy into electrical energy is the

    • Aelectric motor
    • Btransformer
    • Cgenerator
    • Dbattery

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12. Question 92· Electromagnetic induction· WAEC

    A step-up transformer has 50 turns on its primary and 1,000 turns on its secondary. Find the output for a 12 V input.

    • A240 V
    • B0.6 V
    • C600 V
    • D12 V

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13. Question 93· Electromagnetic induction· WAEC

    A transformer has 100 turns on the primary coil and 500 turns on the secondary. If the primary voltage is 20 V, the secondary voltage is

    • A4 V
    • B100 V
    • C2,500 V
    • D400 V

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14. Question 94· Electromagnetic induction· WAEC

    Lenz's law is a consequence of the conservation of

    • Amomentum
    • Bmass
    • Ccharge
    • Denergy

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15. Question 95· Electromagnetic induction· WAEC

    A dynamo converts

    • Amechanical energy into electrical energy
    • Belectrical energy into mechanical energy
    • Cheat into light
    • Dchemical energy into electrical energy

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16. Question 96· Electromagnetic induction· WAEC

    A transformer has 200 turns in its primary and 1000 turns in its secondary. If 12 V a.c. is applied, find the output voltage.

    • A60 V
    • B2.4 V
    • C12 V
    • D240 V

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17. Question 97· Electromagnetic induction· WAEC

    A transformer works only with alternating current because

    • Ad.c. damages the core
    • Bd.c. is too strong
    • Ca.c. has no voltage
    • Dit needs a changing magnetic flux

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18. Question 98· Electrostatics· WAEC

    The instrument used to detect and test small electric charges is the

    • Agalvanometer
    • Bgold-leaf electroscope
    • Cammeter
    • Dvoltmeter

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19. Question 99· Electrostatics· WAEC

    Two like charges

    • Ahave no effect
    • Battract each other
    • Cneutralise
    • Drepel each other

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20. Question 100· Electrostatics· WAEC

    An ebonite rod rubbed with fur becomes

    • Auncharged
    • Bpositively charged
    • Cmagnetised
    • Dnegatively charged

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    Explanation and discussion