Refraction
2 marks · NormalState what is meant by refraction and explain why refraction occurs when a light ray passes from air into water.
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Refraction is the change in direction of a wave as it passes from one medium to another due to a change in speed. It occurs when light slows down as it enters water from air, causing it to bend towards the normal.
Also accept: Refraction is the bending of a wave as it enters a new medium at an angle, due to changing speed.; It happens when the wave slows down or speeds up, causing it to change direction.
Common mistakes: Saying light always bends away from the normal regardless of the direction.; Not mentioning the change of speed.
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Marking points
B1 · 1 mark · Defines refraction as a change of direction of waves due to change in speed
B1 · 1 mark · Explains that this occurs because light travels at different speeds in air and water (slows down entering water)
Worked solution
Refraction is the change in direction of a wave as it passes from one medium to another. It occurs because the speed of the wave, such as light, decreases as it enters water from air, causing the light to bend towards the normal.