# A sound wave travels through air from a loudspeaker to a listener. Explain what is meant by the amplitude, frequency, and wavelength of this sound wave, and state how the speed of the wave is related to its frequency and wavelength.

> WJEC A-Level Physics (Wales) — 3.1 Wave properties · Explain · 5 marks

> A loudspeaker produces a steady musical note. The sound wave travels through the air at 340 m/s.

## Mark scheme (5 marks)

1. Amplitude is the maximum displacement of the air particles from their equilibrium (rest) position
2. Frequency is the number of complete waves (cycles) produced per second
3. Wavelength is the distance between two successive points that are in phase / the length of one complete wave
4. Wave speed equals frequency multiplied by wavelength (v = fλ)
5. If frequency increases, wavelength decreases (for a constant wave speed) / frequency and wavelength are inversely proportional at constant speed

## Key terms

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

## Related

- [Revision notes for WJEC A-Level 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-0246c6db) · Published by Druglandscape Ltd.