# A sound wave travels through air. The wave has a period of 0.002 s and a speed of 340 m/s. Using your knowledge of wave features, explain how the frequency and wavelength of this wave are related to these values, and describe what would happen to the wavelength if the frequency were doubled while the wave speed remained constant.

> WJEC GCSE Physics (Wales) — 1.5 Features of waves · Explain · 4 marks

> Sound waves are longitudinal waves that transfer energy through a medium. Like all waves, they can be described using features such as frequency, period, wavelength, amplitude, and wave speed.

## Mark scheme (4 marks)

1. Frequency is the number of complete waves (cycles) passing a point per second / frequency is the reciprocal of the period
2. Wavelength is the distance between two successive points in phase / distance of one complete wave cycle
3. Wave speed = frequency × wavelength, so frequency and wavelength are inversely proportional when wave speed is constant
4. If frequency is doubled and wave speed stays the same, the wavelength is halved

## Key terms

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

## Related

- [Revision notes for WJEC GCSE Physics (Wales)](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-sound-wave-travels-through-air-976da67d) · Published by Druglandscape Ltd.