# Explain why alpha radiation is considered more hazardous than gamma radiation when a radioactive source is swallowed or inhaled, but less hazardous than gamma radiation when the source is outside the body.

> OCR GCSE Physics A: Gateway Science (J249) — P4.4 Uses and hazards of radiation · Explain · 4 marks

> Radioactive materials can enter the body through ingestion or inhalation. The type of radiation emitted affects how dangerous the source is, depending on whether it is inside or outside the body.

## Mark scheme (4 marks)

1. Alpha radiation has a very short range in air / cannot penetrate skin, so an external alpha source cannot reach internal organs.
2. When inside the body, alpha radiation is heavily ionising / deposits all its energy in surrounding tissue, causing significant damage to cells.
3. Gamma radiation is weakly ionising / passes through the body, so it causes less damage to internal tissue per unit length.
4. An external gamma source is hazardous because gamma radiation is highly penetrating and can reach and ionise internal organs from outside the body.

## Key terms

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

## Related

- [Revision notes for OCR GCSE Physics A: Gateway Science (J249)](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-considered-d7438897) · Published by Druglandscape Ltd.