A narrow beam PQ of white light is passing through a glass prism ABC as shown in the diagram. Trace it one your answer sheet and show the path of the emergent beam as observed on the screen DE.
(i) Write the name and cause of the phenomenon observed.
(ii) Where else is nature is the phenomenon observed ?
(iii) Based on this observation, state the conclusion which can be drawn about the constituents of white light.

Explanation

(i) The phenomenon observed is dispersion of light which means splitting of white light into its constituent colours. It is caused because different constituent colours of light travel with different speeds in the prism and bend through different angles.
(ii) In nature, this pehnomenon is observed in formation of rainbow.
(iii) Based on phenomenon of dispersion, we can conclude that : (a) White light consists of seven colours.
(b) Violet light suffers maximum deviation and red light suffers minimum deviation.