Question

a) Explain the term refraction of light.

(b) Letters written on a paper when seen through a rectangular glass slab appear to be raised. Explain this phenomenon with the help of a ray diagram.

(c) Light enters from air into diamond which the speed of light in diamond. The speed of light in air is 3x108 ms1.

Answer 1

a) refraction of light is the bending of light at the interface from one medium to the other medium
b)this is due to the phenomenon of refraction of light.when the light ray passes in the air and touches the interface of glass slab medium the light ray bends which causes the refraction

Answer 2

A) Refraction of Light :
The change in direction of light when it passes from one medium to another obliquely  is called Refraction of light.

b)The words of writing which are below the glass slab appear raised due to refraction of light as it comes out of glass slab.
Thus, when we look at letters printed on a piece of paper through glass slab obliquely, the light rays bend at air-glass interface and letters appear to be raised.
Please refer the attachment for diagram

C) I think the we need to find speed of light in diamond:
Refractive index of Diamond=speed of light/speed of light in diamond
2.42=3 x 10 8/speed of light in diamond
Speed of light in diamond=3x 10 ⁸/2.42
=1.24 x 10 ⁸m/s