question_answer

The deviation is maximum for which colour?

A)  Violet                                  

B)  Red

C)  Blue                     

D)         Green

Correct Answer: A

Solution :

We know that wavelength of violet light is minimum and that of red light is maximum. \[\therefore \]  \[{{\lambda }_{R}}>{{\lambda }_{V}}\] From Cauchys dispersion relation                 \[\mu \propto \frac{1}{\lambda }\] So,\[{{\mu }_{V}}>{{\mu }_{R}},\,\,ie,\]refractive index of glass for violet light is maximum. Hence, from the formula                 \[{{\delta }_{m}}=(\mu -1)A\] where \[{{\delta }_{m}}\] is angle of deviation and \[A\] the angle of prism, violet light deviates the most and red the least.