# State two properties that are shared by all waves in the electromagnetic spectrum, and for each property, explain why it is significant for the use of electromagnetic waves in communications.

> Cambridge International IGCSE Physics (0625) — 3.3 Electromagnetic spectrum · State and Explain · 4 marks

## Mark scheme (4 marks)

1. All electromagnetic waves are transverse waves
2. Explanation of why being transverse is significant for communications, e.g. they can be polarised / they can carry information encoded in their oscillations
3. All electromagnetic waves travel at the same speed of 3.0 × 10⁸ m/s in a vacuum (or approximately the same speed in air)
4. Explanation of why travelling at this high/same speed is significant for communications, e.g. signals are transmitted very quickly / information can travel vast distances rapidly / signals from different parts of the spectrum arrive simultaneously

## Key terms

- [electromagnetic spectrum](https://www.gradenine.co.uk/glossary/electromagnetic-spectrum)

## Related

- [Revision notes for Cambridge International IGCSE Physics (0625)](https://www.gradenine.co.uk/learn)
- [How to answer "State and 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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