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.

Options

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

A

Explanation

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.