# A sound wave travels through air and then enters water. Describe and explain what happens to the speed, frequency, and wavelength of the sound wave as it moves from air into water.

> Pearson Edexcel International GCSE Physics (4PH1) — 3.1 Properties of waves · Describe and explain · 4 marks

> Sound waves are longitudinal waves that can be refracted when they pass from one medium into another. Water is a denser medium than air.

## Mark scheme (4 marks)

1. The speed of the sound wave increases (as it enters the denser medium of water)
2. The frequency of the sound wave remains unchanged / stays the same
3. The wavelength of the sound wave increases
4. The wavelength increases because speed = frequency × wavelength, and since frequency is constant but speed increases, wavelength must increase

## Key terms

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

## Related

- [Revision notes for Pearson Edexcel International GCSE Physics (4PH1)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe and 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-sound-wave-travels-through-air-36df9a21) · Published by Druglandscape Ltd.