# A student is standing in a swimming pool. The student notices that when they look at their legs through the water, their legs appear to be in a different position from where they actually are. Explain why this happens in terms of what occurs when light travels from water into air.

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

## Mark scheme (4 marks)

1. Light changes speed when it moves from water to air
2. Light is refracted / changes direction at the boundary between water and air
3. The light bends away from the normal as it passes from water into air
4. The observer's brain traces the light back in a straight line, so the legs appear to be in a different (shallower/shifted) position

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