question_answer

The angle of deviation for a prism is greater for:

A)  violet colour                     

B)  blue colour

C)  green colour                    

D)  red colour

Correct Answer: A

Solution :

                When a beam of white light falls on a prism, it splits into the rays of its constituent colours. This is known as dispersion. Reason is that in a material medium the light rays of different colours travel with different speeds. The refractive index of glass is maximum for violet light and minimum for red light. Hence, according to formula\[{{\delta }_{m}}=(n-1)A,\]the angle of deviation for violet light will be greater than angle of deviation for red light.