# Explain what happens to a ray of light as it passes from air into a glass block, and then back out from the glass block into air. Include what happens to the speed and direction of the light at each boundary.

> WJEC A-Level Physics (Wales) — 2.6 Refraction of light · Explain · 5 marks

## Mark scheme (5 marks)

1. Light slows down when it enters the glass from air
2. Light bends towards the normal when entering the glass (at the air-glass boundary)
3. Light speeds up when it leaves the glass and enters air
4. Light bends away from the normal when leaving the glass (at the glass-air boundary)
5. The ray emerging from the glass is parallel to the original incident ray (but displaced)

## Key terms

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

## Related

- [Revision notes for WJEC A-Level Physics (Wales)](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-to-a-ray-43689fbc) · Published by Druglandscape Ltd.