IGCSE Physics Electromagnetic Induction Questions and Worked Solutions (4.5.1) | 0625

By /
IGCSE Physics 0625 · Topic 4.5.1

IGCSE Physics Electromagnetic Induction Questions and Worked Solutions

50 topic-wise practice questions on Electromagnetic Induction (Unit 4: Electricity and Magnetism), written to the Cambridge IGCSE Physics 0625 syllabus for 2026–2028, each with a step-by-step worked solution.

50 questions22 Core18 Extended10 Challenge128 marksTextbook §4.5 · pp. 229–250
Questions tagged Core are for all candidates (Papers 1 & 3). Questions tagged Extended are Supplement content (Papers 2 & 4). Questions 41–50 are harder Challenge questions. Try each question first, then tap Show solution to check your working.

Topic guide: Electromagnetic Induction

Electromagnetic induction: when a conductor moves through a magnetic field, or the field around a conductor changes, an e.m.f. is induced. This is how generators, microphones and transformers work.

Key formulas

No equations to learn in this subtopic — e.m.f. increases with speed, field strength and number of turns.

Prerequisite knowledge

  • Magnetic fields (4.1)
  • e.m.f. (4.2.3)

Exam tips & common mistakes

  • A stationary magnet in a coil induces nothing
  • Reversing motion or the magnet reverses the current
  • Use the RIGHT hand for generators (induced current)

Key facts from the syllabus (4.5.1)

  • An e.m.f. is induced when a conductor cuts magnetic field lines or the field linking it changes
  • Experiment: move a magnet in and out of a coil connected to a sensitive meter; or move a wire between magnet poles
  • Larger e.m.f.: faster motion, stronger magnet, more turns on the coil
  • No change in field → no induced e.m.f.
  • Extended the induced e.m.f. opposes the change causing it (Lenz's law)
  • Extended Fleming's right-hand rule gives the relative directions of motion (thumb), field (first finger) and induced current (second finger)

Textbook: §4.5 Electromagnetic effects, pp. 229–250

1
Core[2 marks]

State two ways of inducing an e.m.f. in a conductor.

Show solutionHide solution

Method: Moving through field; changing field.

Move the conductor across a magnetic field; or change the magnetic field linking the conductor
2
Core[3 marks]

Describe an experiment to demonstrate electromagnetic induction.

Show solutionHide solution

Method: Magnet into coil with galvanometer.

Connect a coil to a sensitive ammeter (galvanometer); push a bar magnet into the coil — the meter deflects; pulling it out gives the opposite deflection; no deflection when the magnet is stationary
3
Core[3 marks]

State three factors that increase the size of an induced e.m.f.

Show solutionHide solution

Method: Speed, field strength, turns.

Faster movement; stronger magnet/field; more turns on the coil
4
Core[1 mark]

A magnet is held still inside a coil. State the induced e.m.f.

Show solutionHide solution

Method: No change.

Zero
5
Core[2 marks]

A magnet is pushed into a coil and the meter deflects left. State what happens when it is pulled out.

Show solutionHide solution

Method: Opposite direction.

The meter deflects to the right (opposite direction)
6
Core[2 marks]

A magnet is pushed into a coil quickly, then slowly. Compare the deflections.

Show solutionHide solution

Method: Rate of change.

The quick push gives a larger deflection
7
Core[2 marks]

A wire is moved parallel to the magnetic field lines. Explain why no e.m.f. is induced.

Show solutionHide solution

Method: No cutting.

The wire does not cut through field lines
8
Core[2 marks]

The S pole instead of the N pole is pushed into the coil. State the effect on the deflection.

Show solutionHide solution

Method: Reverses.

The deflection is in the opposite direction
9
Core[2 marks]

Explain why a bicycle dynamo produces a larger e.m.f. when the bicycle goes faster.

Show solutionHide solution

Method: Faster rate of change.

The magnet rotates faster, so the field changes faster, inducing a larger e.m.f.
10
Core[2 marks]

Give one practical use of electromagnetic induction.

Show solutionHide solution

Method: Generators, transformers.

Generators (dynamos), transformers, microphones
11
Core[1 mark]

State what is meant by an induced e.m.f.

Show solutionHide solution

Method: e.m.f. produced by changing field.

An e.m.f. produced in a conductor by a changing magnetic field (or by moving through a field)
12
Core[2 marks]

A magnet is moved into a coil and then held still. Describe the meter readings.

Show solutionHide solution

Method: Change needed.

A deflection while the magnet moves, then zero when it stops
13
Core[2 marks]

State the effect of using a coil with fewer turns on the induced e.m.f.

Show solutionHide solution

Method: Fewer turns.

The induced e.m.f. decreases
14
Core[2 marks]

State the effect of using a weaker magnet on the induced e.m.f.

Show solutionHide solution

Method: Weaker field.

The induced e.m.f. decreases
15
Core[2 marks]

A coil is moved towards a stationary magnet. State whether an e.m.f. is induced.

Show solutionHide solution

Method: Relative motion.

Yes, because there is relative motion (the field linking the coil changes)
16
Core[3 marks]

Describe how to show electromagnetic induction using a straight wire and a U-shaped magnet.

Show solutionHide solution

Method: Move wire through field.

Connect the wire to a sensitive meter; move the wire up and down between the poles; the meter deflects, in opposite directions for opposite motions
17
Core[2 marks]

State two ways of reversing the direction of an induced current.

Show solutionHide solution

Method: Reverse motion or pole.

Reverse the direction of motion, or reverse the magnetic field (turn the magnet round)
18
Core[2 marks]

Explain why an induced e.m.f. appears in a stationary coil when a nearby electromagnet is switched on.

Show solutionHide solution

Method: Changing field.

The magnetic field linking the coil changes as the current rises
19
Core[2 marks]

State why no e.m.f. is induced in a stationary coil next to an electromagnet carrying a steady current.

Show solutionHide solution

Method: No change.

The field is not changing
20
Core[2 marks]

Name a device that uses electromagnetic induction to convert sound into an electrical signal.

Show solutionHide solution

Method: Microphone.

A (moving-coil) microphone
21
Core[2 marks]

State the energy transfer when a magnet is pushed into a coil connected to a lamp.

Show solutionHide solution

Method: Kinetic → electrical.

Kinetic (work done) → electrical → light and thermal
22
Core[2 marks]

State one factor that does not affect the size of the induced e.m.f. for a moving magnet.

Show solutionHide solution

Method: e.g. coil resistance.

The resistance/colour of the wire (e.m.f. depends on speed, field strength and turns)
23
Extended[1 mark]

State the rule for the direction of an induced e.m.f.

Show solutionHide solution

Method: Lenz's law.

The induced e.m.f. opposes the change causing it
24
Extended[3 marks]

A N pole is pushed towards a coil. State the pole formed at the near end of the coil and explain.

Show solutionHide solution

Method: Opposes motion.

A N pole, which repels the approaching magnet, opposing the change
25
Extended[3 marks]

A N pole is pulled away from a coil. State the pole formed at the near end of the coil and explain.

Show solutionHide solution

Method: Opposes motion.

A S pole, which attracts the magnet, opposing it moving away
26
Extended[2 marks]

Explain why it takes more effort to push a magnet into a coil when the coil is part of a complete circuit.

Show solutionHide solution

Method: Induced current opposes.

The induced current produces a field that opposes the magnet, so work must be done against it
27
Extended[2 marks]

Name the hand rule used to find the direction of induced current in a moving wire.

Show solutionHide solution

Method: Fleming's right-hand rule.

Fleming's right-hand rule
28
Extended[3 marks]

In Fleming's right-hand rule, state what the thumb, first finger and second finger represent.

Show solutionHide solution

Method: Motion, field, current.

Thumb: motion (force); first finger: field; second finger: induced current
29
Extended[3 marks]

A wire moves upwards through a magnetic field pointing into the page. Use Fleming's right-hand rule to state the direction of the induced current.

Show solutionHide solution

Method: Thumb up, first finger into page.

Current flows to the left
30
Extended[2 marks]

Explain why no current flows if the coil is part of an open circuit, even though an e.m.f. is induced.

Show solutionHide solution

Method: Incomplete circuit.

An e.m.f. is induced, but current needs a complete circuit
31
Extended[2 marks]

A magnet is dropped through a coil. Describe the shape of the induced e.m.f. against time.

Show solutionHide solution

Method: Two pulses, opposite signs.

A pulse as it enters, then a larger opposite pulse as it leaves (faster)
32
Extended[2 marks]

State Lenz's law in words.

Show solutionHide solution

Method: Opposes the change.

The direction of an induced e.m.f. is such that it opposes the change producing it
33
Extended[3 marks]

Explain, using energy, why the induced current must oppose the motion of the magnet.

Show solutionHide solution

Method: Conservation of energy.

Work must be done to push the magnet against the opposing force; this work becomes electrical energy. If it helped the motion, energy would be created
34
Extended[3 marks]

A S pole is pushed towards a coil. State the pole at the near end of the coil.

Show solutionHide solution

Method: Opposes approach.

A S pole
35
Extended[3 marks]

A copper ring is dropped over a vertical bar magnet. Explain why it falls more slowly than expected.

Show solutionHide solution

Method: Induced current opposes.

A current is induced in the ring, which produces a field opposing its motion
36
Extended[3 marks]

Use Fleming's right-hand rule: a wire moves into the page through a field pointing to the right. State the direction of the induced current.

Show solutionHide solution

Method: Thumb into page, first finger right.

Downwards
37
Extended[3 marks]

A wire moves to the right through a field pointing out of the page. State the direction of the induced current.

Show solutionHide solution

Method: Right-hand rule.

Downwards (in the plane, perpendicular to motion)
38
Extended[2 marks]

State the relative directions of force (motion), field and induced current in a generator wire.

Show solutionHide solution

Method: Mutually perpendicular.

All three are at right angles to each other
39
Extended[2 marks]

Explain why a magnet falls slowly down a copper tube.

Show solutionHide solution

Method: Eddy currents oppose.

Currents induced in the tube create fields opposing the magnet's motion
40
Extended[3 marks]

Explain why the deflection is larger when a magnet is pulled out of a coil quickly than slowly, with reference to the rate of change.

Show solutionHide solution

Method: Faster change.

The magnetic field linking the coil changes faster, so a larger e.m.f. is induced

Challenge questions

Harder, multi-step questions at the top end of the exam. Attempt these once you are confident with the questions above.

41
ChallengeCore[4 marks]

Describe an experiment with a coil, a magnet and a sensitive ammeter to show three factors that affect the size of an induced e.m.f.

Show solutionHide solution

Method: Vary speed, strength, turns.

Push the magnet in at different speeds (faster → larger deflection), use stronger magnets (larger), and coils with more turns (larger)
42
ChallengeCore[3 marks]

Explain why no current is induced when a magnet rests inside a coil, but a current flows as it is pulled out.

Show solutionHide solution

Method: Changing field needed.

An e.m.f. is induced only when the magnetic field linking the coil changes
43
ChallengeCore[4 marks]

A magnet is dropped through a long coil connected to a data logger. Describe the shape of the e.m.f.–time graph and explain why the second pulse is larger and shorter.

Show solutionHide solution

Method: Accelerating magnet.

A pulse as the magnet enters, then an opposite pulse as it leaves; it is moving faster when leaving, so the second pulse is larger and shorter
44
ChallengeCore[4 marks]

Explain how a moving-coil microphone uses electromagnetic induction to convert sound into an electrical signal.

Show solutionHide solution

Method: Coil moves in field.

Sound vibrates a diaphragm attached to a coil in a magnetic field; the moving coil cuts field lines, inducing a varying e.m.f. that matches the sound
45
ChallengeExtended[4 marks]

Using Lenz's law, explain why a magnet dropped through a copper tube falls more slowly than through a plastic tube.

Show solutionHide solution

Method: Opposing currents.

Currents are induced in the copper tube, producing fields that oppose the magnet's motion; plastic is an insulator so no currents flow
46
ChallengeExtended[4 marks]

A N pole is pushed into a coil. State the pole at the near end of the coil, the direction of the induced current seen from the magnet's side, and explain why.

Show solutionHide solution

Method: Opposes approach.

A N pole forms to repel the magnet; the current flows anticlockwise as seen from the magnet (right-hand grip rule)
47
ChallengeExtended[4 marks]

A straight wire moves upwards between the N (left) and S (right) poles of a magnet. Use Fleming's right-hand rule to find the direction of the induced current.

Show solutionHide solution

Method: Field right, motion up.

Into the page
48
ChallengeExtended[4 marks]

Explain, using energy conservation, why the induced current must oppose the change that caused it.

Show solutionHide solution

Method: Work against opposing force.

Work must be done against the opposing force, and this work becomes electrical energy; if the current helped the motion, energy would be created from nothing
49
ChallengeExtended[4 marks]

An aircraft with a metal wingspan flies horizontally through the Earth's magnetic field. Explain why an e.m.f. is induced between the wing tips but no current flows round the wings.

Show solutionHide solution

Method: Moving conductor, no complete circuit.

The wings cut field lines, inducing an e.m.f.; there is no complete circuit, so no current flows
50
ChallengeExtended[3 marks]

Explain why the deflection of a meter connected to a coil reverses when the magnet is pulled out instead of pushed in.

Show solutionHide solution

Method: Change reverses.

The change in field reverses direction, so the induced e.m.f. reverses
All IGCSE Physics topics← 4.4 Electrical Safety4.5.2 The a.c. Generator →

Book a free trial class

Tell us a little about your requirement.