An audio engineer is testing a high-fidelity moving-coil loudspeaker design. The diagram below shows a simplified cross-section of the loudspeaker.
State the type of electrical supply that must be connected to the coils of wire in the loudspeaker to produce continuous, fluctuating sound waves.
Explain how this electrical supply causes the speaker cone to vibrate and produce sound.
The engineer conducts a series of trials to investigate how the electromagnetic force acting on the coil depends on:
- the magnetic flux density of the permanent magnet
- the current flowing through the coil.
The engineer obtains the following set of measurements:
| Magnetic flux density (BBB / T) | Current (III / A) | Measured Force (FFF / N) |
|---|---|---|
| 0.20 | 0.40 | 0.096 |
| 0.40 | 0.80 | 0.384 |
| 0.60 | 1.20 | 0.864 |
Explain why these experimental results cannot be used to determine how the current alone affects the magnetic force on the coil.
The motor effect Questions
Practise AQA GCSE Physics The motor effect with exam-style questions for Foundation and Higher tier. 25 questions covering Electromagnetism, Fleming's left-hand rule (HT only), Electric motors (HT only), and Loudspeakers (physics only) (HT only), matched to the AQA GCSE Physics (8463) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.