Question -
Answer -
As per the given figure,for the glass − air interface:
Angle of incidence, i = 60°
Angle of refraction, r =35°
The relative refractiveindex of glass with respect to air is given by Snell’s law as:

As per the given figure,for the air − water interface:
Angle of incidence, i = 60°
Angle of refraction, r =47°
Therelative refractive index of water with respect to air is given by Snell’s lawas:

Using (1) and (2), therelative refractive index of glass with respect to water can be obtained as:

The following figure showsthe situation involving the glass − water interface.

Angle of incidence, i = 45°
Angle of refraction = r
From Snell’s law, r can becalculated as:

Hence,the angle of refraction at the water − glass interface is 38.68°.