# Explain why radio waves are used for broadcasting television and radio signals on Earth, whilst microwaves are used for satellite communications. Your answer should refer to the properties of both types of electromagnetic radiation.

> Pearson Edexcel International GCSE Physics (4PH1) — 3.2 The electromagnetic spectrum · Explain · 4 marks

> Radio waves and microwaves are both types of electromagnetic radiation used in communications. Radio waves have wavelengths ranging from about 1 mm to 100 km, whilst microwaves have wavelengths of roughly 1 mm to 30 cm.

## Mark scheme (4 marks)

1. Radio waves are reflected by the ionosphere (a layer of the atmosphere)
2. This reflection allows radio waves to be sent/received over long distances around the curved Earth's surface
3. Microwaves can pass through / penetrate the ionosphere (because they have a shorter wavelength / higher frequency than radio waves)
4. This allows microwaves to be transmitted to and from satellites in orbit above the ionosphere, enabling satellite communications

## Key terms

- [radio waves](https://www.gradenine.co.uk/glossary/radio-waves)
- [microwaves](https://www.gradenine.co.uk/glossary/microwaves)
- [electromagnetic radiation](https://www.gradenine.co.uk/glossary/electromagnetic-radiation)
- [satellite communications](https://www.gradenine.co.uk/glossary/satellite-communications)

## Related

- [Revision notes for Pearson Edexcel International GCSE Physics (4PH1)](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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