Question

(a) What happens when a ray of ordinary light is passed through a triangular glass prism ?
(b) What will happen if another similar glass prism is placed upside down behind the first prism ?

Answer 1

(a) When a ray of ordinary light is passed through a triangular glass prism, it splits to form a band of seven colours.
(b) If another similar glass prism is placed upside down behind the first prism, then the seven coloured rays from the first prism which are incident on the second prism recombine to form the original white beam.