Physics
An obliquely incident light ray bends at the surface due to change in speed, when passing from one medium to other. The ray does not bend when it is incident normally. Will the ray have different speed in the other medium?
Answer
We observe that, when a ray of light passing from one medium to other is obliquely incident it bends at the surface due to change in speed in going from one medium to another.
However, for normal incidence from one medium to another, angle of incidence ∠i = 0° then the angle of refraction ∠r = 0°. Hence the speed of light changes but the direction of light does not change.
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