# Explain how a moving-coil microphone converts sound waves into an electrical signal.

> Eduqas GCSE Physics — 8.4 Microphones, speakers, oscillating currents in detection · Explain · 4 marks

## Mark scheme (4 marks)

1. Sound waves cause the diaphragm to vibrate
2. The vibrating diaphragm causes the attached coil to move (back and forth) inside a magnetic field
3. The moving coil cuts through magnetic field lines, inducing a voltage (e.m.f.) in the coil
4. The induced voltage (and current) is alternating / oscillating, matching the frequency of the original sound wave

## Key terms

- [coil](https://www.gradenine.co.uk/glossary/coil)

## Related

- [Revision notes for Eduqas GCSE Physics](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/explain-how-a-moving-coil-microphone-converts-20215ba5) · Published by Druglandscape Ltd.