WAEC Physics questions: Electromagnetic induction

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

1. Question 1· 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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2. Question 2· 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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3. Question 3· 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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4. Question 4· 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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5. Question 5· Electromagnetic induction· WAEC

   The device that changes mechanical energy into electrical energy is the

   • Aelectric motor
   • Btransformer
   • Cgenerator
   • Dbattery

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6. Question 6· 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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7. Question 7· 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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8. Question 8· Electromagnetic induction· WAEC

   Lenz's law is a consequence of the conservation of

   • Amomentum
   • Bmass
   • Ccharge
   • Denergy

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9. Question 9· 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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10. Question 10· 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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11. Question 11· 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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    Explanation and discussion