# A student investigates how sound travels through different materials. The student finds that sound travels faster through steel than through air. When a sound wave passes from air into steel, explain what happens to the speed, wavelength and frequency of the sound wave.

> Edexcel A-Level Physics (9PH0) — 4.1 Stress, strain and the Young modulus · Explain · 5 marks

> Sound is a longitudinal wave. The speed of sound in air is approximately 340 m/s. The speed of sound in steel is approximately 5800 m/s.

## Mark scheme (5 marks)

1. The speed of the sound wave increases (when passing from air into steel)
2. The wavelength of the sound wave increases
3. The frequency of the sound wave stays the same / does not change
4. Correct reasoning linking speed and wavelength: because frequency is constant and speed increases, wavelength must also increase (use of v = fλ implied or stated)
5. Sound is a longitudinal wave so the oscillations / vibrations of particles are parallel to / in the same direction as the direction of travel / energy transfer

## Key terms

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

## 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-student-investigates-how-sound-travels-601baa41) · Published by Druglandscape Ltd.