# A student observes that when a wave undergoes reflection at a smooth, plane surface, three wave properties remain unchanged. State these three properties and explain why the frequency cannot change during reflection.

> Cambridge International IGCSE Physics (0625) — 3.1 General properties of waves · State and Explain · 4 marks

## Mark scheme (4 marks)

1. States that speed is unchanged during reflection
2. States that wavelength is unchanged during reflection
3. States that frequency is unchanged during reflection
4. Explains that the wave stays in the same medium after reflection, so its speed does not change, and since speed and wavelength are both unchanged, frequency must also remain constant (accept: the wave does not change medium so nothing drives a change in frequency / frequency is a property of the source not the medium)

## Key terms

- [reflection](https://www.gradenine.co.uk/glossary/reflection)
- [frequency](https://www.gradenine.co.uk/glossary/frequency)

## 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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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-observes-that-when-a-7f8861b3) · Published by Druglandscape Ltd.