A ray of light is incident at an angle of `60^(@)` on the face of a prism having refracting angle `30^(@)`. The roy emerging out of the prism makes an angle `30^(@)` with the incident ray. Show that the emergert ray is perpendicular to the face through which, it emerges.

Explanation

According to given problem
`A=30^@, i_1=60^@ and delta=30^@`
and as in prism,
`delta=(i_1+i_2)-A`
`30^@=(60^@+i_2)-30^@ i.e., i_2=0^@`
So the emergent ray is perpendicular to the face from which it emerges
Now as `i_2=0,r_2=0`
But as `r_1+r_2=A, r_1=A=30^@`
So at first face `1 sin 60^@=mu sin 30^@` i.e. `mu=sqrt3`