# Explain why alpha radiation is more ionising than gamma radiation, and why alpha radiation is stopped by a thin sheet of paper whilst gamma radiation can penetrate several centimetres of lead.

> AQA A-Level Physics (7408) — 3.8.1 Radioactivity · Explain · 5 marks

## Mark scheme (5 marks)

1. Alpha particles are large / have a large mass (compared to gamma)
2. Alpha particles carry a charge (2+) so interact strongly with surrounding atoms / electrons
3. Alpha particles transfer energy to many atoms in a short distance, causing dense ionisation
4. Gamma radiation is electromagnetic radiation / has no mass and no charge
5. Gamma radiation interacts weakly with matter so passes through most materials / requires dense materials such as lead to be absorbed

## Key terms

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

## Related

- [Revision notes for AQA A-Level Physics (7408)](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/explain-why-alpha-radiation-is-more-fba82e98) · Published by Druglandscape Ltd.