Question

Explain with diagrams how refraction of incident light takes place from 

(a) rarer to denser medium 

(b) denser to rarer medium 

(c) normal to the surface separating the two media.

Answer 1

(a) rarer to denser medium:

When a ray of light travels from optically rarer medium to optically denser medium, it bends towards the normal.

(b) denser to rarer medium: 

When a ray of light travels from an optically denser medium to an optically rarer medium it bends away from the normal.

(c) normal to the surface separating the two media:

A ray of light incident normally on a denser medium, goes without any deviation.