# Explain why radio waves are used to transmit signals over long distances through the atmosphere, whilst gamma rays are not used for this purpose.

> OCR GCSE Physics A: Gateway Science (J249) — P4.2 The electromagnetic spectrum · Explain · 4 marks

> Broadcasting companies transmit television and radio signals across the country using different parts of the electromagnetic spectrum. The choice of wave depends on the properties of that part of the spectrum.

## Mark scheme (4 marks)

1. All electromagnetic waves travel at the same speed in a vacuum / through the atmosphere
2. Radio waves have a long wavelength / low frequency compared to gamma rays
3. Radio waves are not absorbed (significantly) by the atmosphere / can pass through the atmosphere
4. Gamma rays are absorbed by the atmosphere / gamma rays are ionising and harmful / gamma rays do not penetrate the atmosphere over long distances

## Key terms

- [radio waves](https://www.gradenine.co.uk/glossary/radio-waves)
- [gamma rays](https://www.gradenine.co.uk/glossary/gamma-rays)

## 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-radio-waves-are-used-74a7d2b1) · Published by Druglandscape Ltd.