Lesson 3.7.5.4

3.7.5.4 Electromagnetic induction Quiz: AQA Physics, Unit 7

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.7.5.4, Electromagnetic induction: 20 multiple choice questions for the AQA Physics (7408), Unit 7: Fields and their consequences (A-level only), written with Revision Ninja.

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The 20 questions

  1. What does Faraday's law state about the magnitude of an induced emf?

    • It equals the flux linkage divided by the time taken
    • It equals the current multiplied by the flux linkage
    • It equals the rate of change of flux linkage
    • It equals the flux density multiplied by the coil area

  2. What does Lenz's law state about the direction of an induced current?

    • It flows in a direction that opposes the change producing it
    • It flows in the same direction as the change in flux, to add to it
    • It always flows in the direction that increases the change in flux
    • It is independent of the direction in which the flux is changing

  3. Which equation gives the induced emf in a coil of N turns when the flux changes by delta Phi in time delta t?

    • emf = N x delta Phi / delta t
    • emf = N x Phi / delta t
    • emf = N x B x delta t / A
    • emf = N x delta Phi / delta t squared

  4. A 200-turn coil has flux changing from 0 to 5.0 x 10^-4 Wb in 0.10 s. What is the average induced emf?

    • 0.10 V
    • 1.0 V
    • 10 V
    • 0.010 V

  5. A straight conductor of length 0.25 m moves at 4.0 m/s perpendicular to a field of 0.20 T. What emf is induced across it?

    • 3.2 V
    • 0.80 V
    • 0.20 V
    • 0.050 V

  6. A 50-turn coil of area 0.020 m^2 rotates uniformly in a field of 0.10 T at angular speed 100 rad/s. What is the peak emf?

    • 100 V
    • 5.0 V
    • 1.0 V
    • 10 V

  7. A 100-turn coil of area 0.02 m^2 in a field of 0.05 T rotates at 50 Hz. What is the peak emf?

    • 157 V
    • 16 V
    • 1.6 V
    • 0.16 V

  8. The flux through a single-turn coil changes uniformly from 0.040 Wb to 0.010 Wb in 0.02 s. What is the induced emf?

    • 1.5 V
    • 0.030 V
    • 0.50 V
    • 3.0 V

  9. A north pole is pushed into a coil. What pole does the induced current produce at the face nearer the magnet?

    • a north pole, which repels the magnet
    • a north pole, which attracts the magnet
    • no pole, since an induced current produces no magnetic field
    • a south pole, which attracts the magnet

  10. At what point in its rotation does a coil in a uniform field have its maximum induced emf?

    • when its plane is parallel to the field, since the rate of change of flux is then greatest
    • the emf is constant at all angles of rotation
    • when its flux linkage is greatest, at the normal position
    • when its plane is perpendicular to the field, since the flux is then greatest

  11. A 0.50 m rod moves at 2.0 m/s across a field of 0.40 T and is part of a 25 ohm circuit. What current flows?

    • 16 mA
    • 1.6 mA
    • 160 mA
    • 0.40 A

  12. Why must Lenz's law hold, linked to conservation of energy?

    • A magnet is repelled by any changing field whatever its motion
    • The induced emf depends only on the speed of the magnet
    • An aiding induced current would create energy from nothing as the magnet was pushed in
    • Induced currents always flow in the coil's own direction whatever the change

  13. A 400-turn coil has flux falling from 3.0 mWb to zero in 0.25 s. What is the average emf?

    • 0.0030 V
    • 4.8 V
    • 1.2 V
    • 0.48 V

  14. A 100-turn coil of area 0.0050 m^2 in a field of 0.40 T turns from normal alignment to parallel in 0.020 s. What is the average emf?

    • 20 V
    • 0.20 V
    • 5.0 V
    • 10 V

  15. A 0.30 m rod moves at 1.5 m/s across a field of 0.25 T. What emf is developed across its ends?

    • 0.11 V
    • 0.045 V
    • 1.1 V
    • 0.75 V

  16. A 100-turn coil has an induced emf of 2.0 V. What is the rate of change of flux?

    • 0.020 Wb/s
    • 2.0 Wb/s
    • 200 Wb/s
    • 0.0020 Wb/s

  17. A loop of area 0.030 m^2 lies normal to a field that changes at 0.50 T/s. What emf is induced?

    • 1.5 V
    • 0.015 V
    • 0.0015 V
    • 0.15 V

  18. The induced emf in a coil is doubled. Which change is consistent with Faraday's law?

    • The total flux change is halved
    • The time taken for the flux change is doubled
    • The rate of change of flux linkage is doubled
    • The number of turns is halved and the time is doubled

  19. A 40-turn coil has a constant induced emf of 0.60 V. What is the rate of change of flux?

    • 0.015 Wb/s
    • 0.15 Wb/s
    • 1.5 Wb/s
    • 0.024 Wb/s

  20. A flat coil rotates with angular speed omega in a uniform field. If omega is doubled with N, B and A unchanged, what happens to the peak emf?

    • It halves
    • It doubles
    • It quadruples
    • It is unchanged

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