# Explain what happens when a wave travelling through one medium reaches the boundary with a different medium.

> Eduqas GCSE Physics — 5.2 Waves at material interfaces · Explain · 4 marks

> When light travels through glass and reaches the boundary with air, some of the light passes through and some does not.

## Mark scheme (4 marks)

1. Some of the wave is reflected at the boundary
2. Some of the wave is transmitted through the boundary into the new medium
3. The transmitted wave changes direction / is refracted as it crosses the boundary
4. The change in direction occurs because the wave changes speed in the new medium

## Key terms

- [boundary](https://www.gradenine.co.uk/glossary/boundary)
- [medium](https://www.gradenine.co.uk/glossary/medium)

## Related

- [Revision notes for Eduqas GCSE Physics](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-what-happens-when-a-wave-d2dea355) · Published by Druglandscape Ltd.