# A scientist is investigating a radioactive sample in a laboratory. The sample emits alpha, beta and gamma radiation. Describe how the scientist could identify which type of radiation is being emitted by using different absorbing materials, and explain why each material is chosen.

> Eduqas A-Level Physics — 6.1 Radioactivity · Describe · 5 marks

> Radioactive materials can emit alpha particles, beta particles and gamma rays. Each type of radiation has different penetrating properties.

## Mark scheme (5 marks)

1. Place a sheet of paper (or a few centimetres of air) between the source and detector — if radiation is stopped, alpha is present
2. Alpha radiation is chosen because it has the least penetrating power / is the least penetrating type of radiation
3. Place a few millimetres of aluminium between the source and detector — if radiation is now stopped, beta is present
4. Beta radiation is chosen because it has greater penetrating power than alpha but is stopped by aluminium
5. Several centimetres of lead (or thick concrete) is needed to reduce gamma radiation, as it is the most penetrating type and cannot be fully stopped

## Key terms

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

## Related

- [Revision notes for Eduqas A-Level Physics](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-scientist-is-investigating-a-radioactive-d265068a) · Published by Druglandscape Ltd.