A ray of light is inclined to one face of a prism at an angle of `60^@`. If angle of prism is `60^@` and the ray deviated through an angle of `42^@` find the angle which the emergent ray makes with second face of the prism.

Answer

`18^@`

Explanation

Here `i_1 = 90^@ - 60^@ = 30^@, A = 60^@`,
`delta = 426@ , (90 - i_2) = ?`
Use `i_1 + i_2 = A + delta`
Remember that `i_1,i_2` are angles with normal to the faces of the prism.