Question

Why refraction of light is zero when light falls par perpendicularly on the median rather than when light incident in any other direction?

Answer 1

Because when the light falls on any denser medium perpendicularly then its rays falls directly on the material so when it again goes from denser to rarer medium then it doesn't show any deflection, it doesn't move towards the normal and away from normal. So, it have to perpendicularly.

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