Question

A very thin narrow beam of white light is made incident on three glass objects shown below.

Comment on the nature and behaviour of the emergent beam in all the three cases.

There is a similarity between two of the emergent beams. Identify the two.

When light enters from air to glass, the angles of incidence and refraction in air and glass are 45°. and 30°, respectively. Find the refractive index of glass.

(Given that sin 45° =1/√2; sin 30°=1/2)

Answer 1

In (i) emergent beam is white and laterally displaced. 

In (ii) emergent beam js a spectrum of seven colours bent in different angles.

In (iii) emergent beam from the second prism is white only. 

The similarity between (i) and (iii) as both emergent rays are white in colour.