AQA GCSE Physics Physics Paper 2 (Higher), June 2024: Question 8
8 marks · Standard Demand difficulty · Short Answer
Investigate electromagnetic induction, induced potential, and the operation of a moving-coil microphone using apparatus with magnets, wires, and ammeters.
Practise this questionQuestion
Question text
08 Figure 13 shows some apparatus used by a teacher in a demonstration.
Figure 13
The teacher moved the wire upwards between the magnets.
The needle on the ammeter deflected to a value of +0.4 mA and then returned
to zero.
08.1 What effect did this demonstrate?
[1 mark]
08.2 Explain why a current was detected when the wire in Figure 13 was moved upwards.
[3 marks]
08.3 The teacher reversed the direction of the magnetic field.
The teacher replaced the wire in its original position.
The teacher moved the wire upwards in the same way as before.
What was the deflection of the needle on the ammeter?
[1 mark]
Tick ( ) one box.
The needle will deflect to –0.4 mA.
The needle will not move.
The needle will deflect to +0.4 mA.32
08.4 Figure 14 shows a sound wave incident on the diaphragm of a
moving-coil microphone.
The inside of the microphone includes a small coil of wire and a magnet.
Figure 14
Explain why the sound waves have an effect on the electric circuit.
[3 marks]
Mark scheme
Show the mark scheme
Question 8
AO /
Question Answers Extra information Mark
Spec. Ref.
08.1 generator (effect) allow electromagnetic induction 1 AO1
4.7.3.1
AO /
Spec. Ref.
08.2 wire cuts through the magnetic 1 AO1
field (between the magnets) 4.7.3.1
a potential difference was 1
induced (across the wire)
as it was part of complete circuit
(there was a current in the 1
circuit)
AO /
Spec. Ref.
08.3 the needle will deflect to –0.4 1 AO3
mA 4.7.3.1
AO /
Spec. Ref.
08.4 (the pressure variations in) the allow air particles collide with 1 AO1
sound (waves) cause the diaphragm causing it to vibrate 4.7.3.3
diaphragm to vibrate
diaphragm moves is insufficient
do not accept moves the
diaphragm up and down
the diaphragm causes the coil / do not accept moves the coil / 1
wire to vibrate wire up and down
(the coil repeatedly changes 1
direction) inducing an alternating
current (in the circuit)
if MP1 and MP2 do not score,
allow sound (waves) cause the
coil / wire to vibrate for– 1 mark– –
Total Question 8 8
How to answer it
Electromagnetic Induction & Moving-Coil Microphones
What this question tests
This question assesses your understanding of electromagnetic induction (the generator effect) and how it applies to practical situations, including simple wire-and-magnet demonstrations and real-world devices like moving-coil microphones. You will need to recall key definitions, explain sequential physical processes step-by-step, and predict how reversing magnetic fields affects induced current.
Naming the Effect
✅ Correct Answer
Generator (effect)
(Allow: electromagnetic induction)
💡 Key Knowledge
When a conductor (like a wire) moves relative to a magnetic field, a potential difference is induced across its ends. This fundamental physics principle is called the generator effect or electromagnetic induction.
Explaining Induced Current (3-Mark Sequence)
✅ Correct Answer
- Point 1: The wire cuts through the magnetic field lines.
- Point 2: A potential difference is induced across the wire.
- Point 3: Because it is part of a complete circuit, a current is driven through the circuit.
🧠 Exam Technique
This is a classic 3-mark causal sequence. To get full marks, you must describe the steps in chronological order: Movement → Cutting field → Induced p.d. → Complete circuit → Current flows. Missing out the mention of a "complete circuit" will cost you the third mark.
❌ Common Errors
Students often state that "the wire creates electricity" or "movement causes a current." Examiners strictly require reference to cutting the magnetic field lines, inducing a potential difference, and having a complete circuit.
Effect of Reversing the Magnetic Field
✅ Correct Answer
The needle will deflect to -0.4 mA. (Tick the first box)
💡 Key Knowledge
Reversing either the direction of motion or the direction of the magnetic field reverses the direction of the induced potential difference and current. Since the original deflection was +0.4 mA , reversing the magnetic field flips the current to -0.4 mA .
How a Moving-Coil Microphone Works
✅ Correct Answer
- Point 1: Sound waves cause the diaphragm to vibrate (due to pressure variations).
- Point 2: The diaphragm causes the attached coil of wire to vibrate (move back and forth within the magnetic field).
- Point 3: As the coil moves, it repeatedly changes direction, inducing an alternating current in the electric circuit.
🧠 Exam Technique
Structure your answer logically following the energy/signal chain: Sound wave → Diaphragm movement → Coil movement → Cutting field → Alternating current. Make sure you use the word vibrate or specify back-and-forth motion; simply saying "moves" is often deemed insufficient by examiners.
❌ Common Errors
A frequent error is stating that "sound electricity is generated." Remember, microphones convert sound waves into electrical signals (alternating current) via electromagnetic induction. Vague descriptions like "moving the coil up and down" will lose marks because sound waves cause oscillations in both directions.
Topics
Physics · P7: Magnetism and Electromagnetism · P6: Waves
Question and mark scheme from the AQA GCSE Physics examination, Physics Paper 2 (Higher), June 2024. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.