A ray of light traveling from a medium x enters obliquely into another medium Y. If it bends away from the normal, then state which one of the two is relatively optically denser. Why?
When the ray of light travels from denser medium to the rarer medium than it bends away from the normal.
Therefore medium x is optically denser than medium y because the ray of light bends away from the normal when it travels from the medium x to medium y.
Figure below shows the situation.
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