A ray of light is incident at an angle of `60^(@)` on one face of a prism of angle `30^(@)`. The ray emerging out of the prism makes an angle of `30^(@)` with the incident ray. The emergent ray is

Options

A. `0^(@)`
B. `90^(@)`
C. `30^(@)`
D. `45^(@)`

Answer

B

Explanation

Incidence angle on one face of a prism,
`i=60^(@)`
Angle of prism, `A=30^(@)`
Emergent ray that makes an angle `30^(@)` with incident ray.
we know, deviation angle, `delta` =
Angle between the incident ray and emergent ray= `30^(@)`
`delta=i+e-A`
`30=60+e-30^(@)`
`rArr e=0^(@)`
So, angle with the face `90^(@)`