A beam of white light is shone onto a glass prism. The light cannot be:(a) deviated (b) dispersed (c) focused (d) refracted

(c) focussed

Explanation

A beam of white light when shone onto a glass prism, it can be deviated, dispersed, or refracted, but it cannot be focussed.

It can be seen in the figure given below that when a beam of white strikes the glass prism it gets refracted towards the normal as it is coming from rarer medium (air) to denser medium (glass). As it enters the glass prism, dispersion occurs and the beam of white light splits into its seven constituent colours. Now, when all the seven colours come out of the prism they get deviates at a different-different angle.