# A student is using a signal generator connected to a loudspeaker to produce sound waves in a room. Explain what is meant by a sound wave, describing how the wave transfers energy through the air and distinguishing it from a transverse wave.

> WJEC A-Level Physics (Wales) — 2.4 The nature of waves · Explain · 5 marks

> Sound is produced when a loudspeaker cone vibrates back and forth, creating disturbances in the surrounding air.

## Mark scheme (5 marks)

1. Sound is a longitudinal wave
2. The particles of air vibrate parallel to (in the same direction as) the direction of energy transfer / wave travel
3. The wave produces regions of compression (particles pushed closer together) and rarefaction (particles spread further apart)
4. Energy is transferred in the direction the wave travels / from the loudspeaker outwards, but the air particles themselves do not travel — they only vibrate about a fixed point
5. In a transverse wave the particles vibrate at right angles (perpendicular) to the direction of energy transfer / wave travel, whereas in a longitudinal wave they vibrate parallel

## Key terms

- [transverse wave](https://www.gradenine.co.uk/glossary/transverse-wave)

## 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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-is-using-a-signal-14cf8002) · Published by Druglandscape Ltd.