Question

Dispersion of white light occurs because different colours of white light undergo different extents of refraction. The dispersion is not evident in a glass slab like it is evident in a prism because the two refracting surfaces are parallel to each other.

• A. True
• B. False

Answer 1

The correct option is A

True

In a glass slab dispersion of white light do take place as the light enters from air to glass. But they become parallel once again as they exit from the other end of the slab. This is because both the refracting faces are parallel to each other. These parallel rays are hard to recognize individually as they are very close to each other. But in a prism the emitted rays are not parallel and over some distance they diverge enough to be recognizable as rays of different colours.