Question

A ray of light is incident at an angle of `60^@` on the face of a prism having refracting angle `30^@.` The ray emerging out of the prism makes an angle `30^@` with the incident ray. Show that the emergent ray is perpendicular to the face through which it emerges.
A. Normal to the face through which it emerges
B. Inclined at `30^(@)` to the face through which it emerges
C. Inclined at `60^(@)` to the face through which it emerges
D. None of these

Answer 1

Correct Answer - A
We know that `delta=i+e-Aimplies e=delta+A-i`
`=30^(@)+30^(@)-60^(@)=0^(@)`
`:.` Emergent ray will be perpendicular to the face.
Therefore if will make an angle of `90^(@)` with the face through which it emerges.