# A loudspeaker is connected to the output of an audio amplifier. Explain how the loudspeaker produces sound waves from the electrical signal it receives.

> Edexcel A-Level Physics (9PH0) — 13.1 Simple harmonic motion and damping · Explain · 5 marks

> A loudspeaker contains a fixed permanent magnet and a coil of wire attached to a cone. When an alternating current from an amplifier passes through the coil, sound is produced.

## Mark scheme (5 marks)

1. The alternating current flows through the coil (in the magnetic field of the permanent magnet)
2. The magnetic field from the current interacts with the magnetic field of the permanent magnet
3. This causes the coil to move / experience a force
4. Because the current is alternating, the coil (and cone) vibrate / move back and forth repeatedly
5. The vibrating cone creates pressure variations in the surrounding air, producing sound waves

## Key terms

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

## Related

- [Revision notes for Edexcel A-Level Physics (9PH0)](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)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-loudspeaker-is-connected-to-the-4c2eba4c) · Published by Druglandscape Ltd.