# A police siren produces a sound wave. Explain what is meant by the amplitude and frequency of this sound wave, and describe how each property affects what a listener hears.

> Eduqas GCSE Physics — 1.5 Features of waves · Explain · 4 marks

> A police car drives past a bystander, sounding its siren. The siren produces a sound wave that travels through the air to the bystander's ears.

## Mark scheme (4 marks)

1. Amplitude is the maximum displacement of a particle from its rest/equilibrium position
2. Greater amplitude means the sound is louder / amplitude determines the loudness (volume) of the sound
3. Frequency is the number of complete waves (cycles/oscillations) passing a point per second
4. Higher frequency means the sound has a higher pitch / frequency determines the pitch of the sound

## Key terms

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

## 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)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-police-siren-produces-a-sound-aa1dfda9) · Published by Druglandscape Ltd.