# A student investigates the refraction of light as it passes from air into a glass block. The student observes that the light ray bends towards the normal as it enters the glass. Explain why the light ray changes direction, and describe what happens to the speed and wavelength of the light as it enters the glass.

> Edexcel A-Level Physics (9PH0) — 4.1 Stress, strain and the Young modulus · Explain · 5 marks

> Light travelling through air enters a rectangular glass block at an angle to the normal at the surface.

## Mark scheme (5 marks)

1. The light changes medium (from air to glass)
2. The speed of light decreases as it enters the glass
3. Because the speed decreases, the light bends towards the normal
4. The frequency of the light remains constant / unchanged
5. The wavelength of the light decreases

## Key terms

- [refraction](https://www.gradenine.co.uk/glossary/refraction)
- [normal](https://www.gradenine.co.uk/glossary/normal)
- [wavelength](https://www.gradenine.co.uk/glossary/wavelength)

## Related

- [Revision notes for Edexcel A-Level Physics (9PH0)](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/a-student-investigates-the-refraction-of-1ae7de3d) · Published by Druglandscape Ltd.