Question

A beam of light is incident on an equilateral glass prism at an angle of ${45}^o$ and emerges out an angle of ${35}^o$. Calculate the angle of deviation of the light beam.

Answer 1

We have studied that,
Angle of deviation ( $\delta$ ) = ( i + e - A )
where, i = angle of incidence
e = angle of emergence
A = Angle of prism
Since, Prism is equilateral:
∴ $\angle A$ = ${60}^o$
On substituting the given values, we get
$\delta$ = ( 45 + 35 - 60 ) = ${20}^o$