# A loudspeaker contains a coil attached to a cone placed inside a magnetic field. Explain how the loudspeaker produces sound when an alternating current is supplied to the coil.

> Pearson Edexcel International GCSE Physics (4PH1) — 6.2 Electromagnetism · Explain · 4 marks

> A loudspeaker is connected to an audio amplifier. The amplifier supplies an alternating current at a frequency of 440 Hz to the coil of the loudspeaker.

## Mark scheme (4 marks)

1. The alternating current causes a force on the coil (due to the motor effect / the interaction of the current with the magnetic field)
2. As the current alternates (changes direction), the force on the coil reverses direction repeatedly
3. The coil is pushed away and pulled back (oscillates / vibrates), causing the attached cone to vibrate
4. The vibrating cone produces sound waves at the same frequency as the alternating current (440 Hz produces a 440 Hz sound)

## Key terms

- [loudspeaker](https://www.gradenine.co.uk/glossary/loudspeaker)
- [alternating current](https://www.gradenine.co.uk/glossary/alternating-current)
- [magnetic field](https://www.gradenine.co.uk/glossary/magnetic-field)

## Related

- [Revision notes for Pearson Edexcel International GCSE Physics (4PH1)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-loudspeaker-contains-a-coil-attached-29813571) · Published by Druglandscape Ltd.