Light long 4

Question 1

What is Refraction of light ?

Answer 1

When travelling obliquely from one medium to another, the direction of propagation of light in the second medium changes. This phenomenon is known as refraction of light.

Question 2

Why is the emergent ray parallel to the direction of
the incident ray ?

Answer 2

The extent of bending of the ray of light at the opposite parallel faces, the air-glass interface, and the glass-air interface of the rectangular glass slab is equal and opposite. This is why the ray of light emerging out of the glass slab is always parallel to the incident ray.

Question 3

What are the laws of refraction ?

Answer 3

(i) The incident ray, the refracted ray and the normal to the interface of two transparent media at the point of incidence, all lie in the same plane.

(ii) The ratio of sine of angle of incidence to the sine of angle of refraction is a constant, for the light of a given colour and for the given pair of media.

This law is also known as Snell’s law of refraction.