# A radioactive source emits beta particles. Describe the nature of a beta particle and explain why beta particles are less ionising than alpha particles.

> WJEC GCSE Physics (Wales) — 2.7 Types of radiation · Describe and Explain · 4 marks

## Mark scheme (4 marks)

1. A beta particle is a fast-moving electron (emitted from the nucleus).
2. A beta particle has a much smaller mass than an alpha particle.
3. Because of its smaller mass (and charge), a beta particle interacts less strongly with atoms it passes through.
4. So beta particles cause fewer ionisations per unit length / per centimetre of path compared to alpha particles.

## Key terms

- [beta particle](https://www.gradenine.co.uk/glossary/beta-particle)
- [ionising](https://www.gradenine.co.uk/glossary/ionising)
- [alpha particle](https://www.gradenine.co.uk/glossary/alpha-particle)

## Related

- [Revision notes for WJEC GCSE Physics (Wales)](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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-radioactive-source-emits-beta-particles-53b72490) · Published by Druglandscape Ltd.