Question

What is dispersion of white light ? State its cause. Draw a diagram to show dispersion of a beam of white light by a glass prism.

Assertion (A) : A rainbow is an artificial spectrum of white light appearing in the sky after a rain shower. Reason (R) : The water droplets act like small prisms.

In the given diagram a beam of white light passed through a glass prism which split into band of seven colours with lower colour P and upper colour Q

State the cause of dispersion of white light by a glass prism. How did Newton using two identical glass prisms, show that white light is made of seven colours? Draw the ray diagram in support of above activity.