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Chapter 17 Practice Paper: Magnetism and electromagnetism — question paper

QuizQuipPractice Series
QQ/GCSE-PHYS/CH17

GCSE (9–1) · GCSE Physics (Foundation and Higher (includes Physics-only content))

Chapter 17 Practice Paper

Magnetism and electromagnetism

Duration: 40 minutes
Total: 30 marks
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READ THESE INSTRUCTIONS FIRST

  • Answer all questions.
  • Section A contains ten multiple-choice questions. Choose one answer, A, B, C or D, for each.
  • Section B contains structured questions. Write your answers in the spaces provided.
  • You may use a calculator.
  • The number of marks is given in brackets [ ] at the end of each question or part question.
  • The total mark for this paper is 30.

Original practice material written for the MOE GCSE Physics syllabus. It is not an official MOE or school examination paper. Chapter 17: magnetic fields, solenoids and electromagnets, the motor effect F = B I L (Higher), DC motors, the generator effect, microphones and loudspeakers (Physics only), transformers (Higher) and the National Grid.

For Examiner’s Use
Section A/ 10
Section B/ 20
Total/ 30

Section A: Multiple-choice questions[10 marks]

Choose one answer for each question. Each question is worth 1 mark.

  1. 1

    A north pole is brought near a south pole. They

    1. Arepel
    2. Bspin
    3. Ccancel out
    4. Dattract
    ( )
  2. 2

    Outside a magnet, field lines point

    1. Ain circles
    2. Bfrom north pole to south pole
    3. Cfrom south pole to north pole
    4. Dtowards the compass needle
    ( )
  3. 3

    Which does NOT make an electromagnet stronger?

    1. Amore turns
    2. Bmore current
    3. Can iron core
    4. Da longer plastic core
    ( )
  4. 4

    The force on a current-carrying wire in a magnetic field is called the

    1. Amotor effect
    2. Bgenerator effect
    3. Ctransformer effect
    4. Dfield effect
    ( )
  5. 5

    A wire of length 0.10 m carries 2.0 A perpendicular to a 0.20 T field. The force is

    1. A0.040 N
    2. B0.0040 N
    3. C0.40 N
    4. D4.0 N
    ( )
  6. 6

    A potential difference is induced in a coil when

    1. Athe coil is heated
    2. Ba steady current flows in it
    3. Cthe magnetic field through it changes
    4. Dits resistance falls
    ( )
  7. 7

    A transformer requires

    1. Aalternating current in the primary
    2. Bdirect current in the primary
    3. Cno current at all
    4. Da plastic core
    ( )
  8. 8

    In a step-up transformer, the secondary voltage rises while the secondary current

    1. Arises too
    2. Bfalls by the same factor
    3. Cstays the same
    4. Dbecomes zero
    ( )
  9. 9

    A transformer’s primary has 50 turns with 230 V across it; the secondary has 500 turns. The secondary voltage is

    1. A23 V
    2. B2 300 V
    3. C230 V
    4. D4.6 V
    ( )
  10. 10

    The National Grid uses very high transmission voltages to

    1. Aspeed up electricity
    2. Bincrease the current in cables
    3. Creduce I²R heating losses in cables
    4. Davoid using transformers
    ( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided.

  1. 11

    A scrapyard crane uses a large electromagnet to lift and release steel car bodies.

    1. (a)

      Describe how the crane operator’s electromagnet is made.

      [2]
    2. (b)

      Explain why the electromagnet rather than a permanent magnet is used.

      [2]
    3. (c)

      State two changes that would increase the magnet’s lifting strength.

      [2]
    4. (d)

      Explain why aluminium bodies could not be lifted this way.

      [1]
  2. 12

    A wire of length 0.25 m carries a current of 4.0 A at right angles to a magnetic field of flux density 0.15 T. (Higher)

    1. (a)

      State the equation linking force, flux density, current and length.

      [1]
    2. (b)

      Calculate the force on the wire.

      [3]
    3. (c)

      State how the force changes if the flux density doubles.

      [1]
    4. (d)

      State the rule for finding the direction of the force.

      [2]
  3. 13

    A laptop charger’s transformer takes 230 V from the mains and delivers 12 V; its primary coil has 1 150 turns. (Higher, Physics only)

    1. (a)

      Calculate the number of turns on the secondary coil.

      [3]
    2. (b)

      Explain why the charger would not work from a 230 V DC supply.

      [2]
    3. (c)

      State the assumption behind the turns-ratio calculation.

      [1]

— End of paper —