Question
Question: A ray of light strikes a plane mirror at an angle of incidence 45<sup>0</sup> as shown in figure. Af...
A ray of light strikes a plane mirror at an angle of incidence 450 as shown in figure. After reflection, the ray passes through a prism of refractive index 1.50, whose apex angle is 40. Through what angle must the mirror be rotated if the total deviation of the ray is to be 900.-
A
20in clock wise
B
10 in clock wise
C
10 in anti clock wise
D
20 in anti clock wise direction
Answer
20in clock wise
Explanation
Solution

if mirror is rotated by 10 in anticlockwise direction ray incident on prism will make 20 with previous incident ray and after parssing through prism it will suffer deviation in clockwise direction of 20. So it will become parallel to previous incident ray and deviation become of 900