Question

pexxx explain refraction through a glass slab

Answer 1

pls see the attachment.

Answer 2

Refraction through a rectangular glass slab

To understand the refraction of light through a glass slab consider the figure given below which shows the refraction of light through a rectangular glass slab.
Here in this figure AO is the light ray travelling in air and incident on glass slab at point O.

Now on entering the glass medium this ray bends towards the normal NN’ that is light ray AO gets refracted on entering the glass medium.

After getting refracted this ray now travels through the glass slab and at point B it comes out of the glass slab as shown in the figure.

Since ray OB goes from glass medium to air it again gets refracted and bends away from normal N1N'1 and goes in direction BC.

Here AO is the incident ray and BC is the emergent ray and they both are parallel to each other and OB is the refracted ray.

Emergent ray is parallel to incident ray because the extent of bending of the ray of light at the opposite parallel faces which are PQ (air-glass interface) and SR (glass-air interface) of the rectangular glass slab is equal and opposite.

In the figure i is the angle of incidence, r is the angle of refraction and e is the angle of emergence.

Angle of incidence and angle of emergence are equal as emergent ray and incident ray are parallel to each other.

When a light ray is incident normally to the interface of two media then there is no bending of light ray and it goes straight through the medium.

hope this is useful to you