Question

The angle of a prism is 60 .When light is incident at an angle of 60 on the prism,the angle of emergence is 40. The angle of incidence i for which the light ray will deviate the least is such that :

• A. i < 40
• B. 40 < i < 50
• C. 50 < i <60
• D. i > 60

Answer 1

The correct option is B 40 < i < 50

i=e

$r_1=r_2=\frac{A}{2}$

$\therefore r_1=r_2=30$

For minimum devation i should lie between 40 to 50