Question
Physics Question on Ray optics and optical instruments
The refractive index of the material of a prism is 2 and its refracting angle is 30º. One of the refracting surfaces of the prism is made a mirror inwards. A beam of monochromatic light entering the prism from the other face will retrace its path after reflection form the mirrored surface if its angle of incidence on the prism is
A
60º
B
0º
C
30º
D
45º
Answer
45º
Explanation
Solution
If the refractive index of a prism is 2 and one of the refracting surfaces is made into a mirror inwards, a beam of monochromatic light entering the prism from the other face will retrace its path after reflection if its angle of incidence on the prism is 0º.