Question

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 a ray diagram to show the path of a narrow beam of white light, through a combination of two identical prisms arranged together in inverted position with respect to each other, when it is allowed to fall obliquely on one of the faces of the first prism of the combination.

Answer 1

because different colour bend at different lengths
newton prove it by taking two laterally inverted prism he passes the light from 1st prism and light deviates into seven colour then seven colour passes form another prism then they get back converted into white light ..in this way he proove..

Answer 2

I hope this will help you