Question

A ray of light is incident on a ${60}^o$ prism at the minimum deviation position. The angle of refraction at the lines face(i.e., incident face) of the prism is?

• A. ${30}^o$
• B. ${45}^o$
• C. ${60}^o$
• D. Zero

Answer 1

The correct option is A ${30}^o$

$\begin{array}{c}\text{At minimum deviation}\\ i=e,r_1+r_2=A\text{and}{r}_1=r_2\\ \text{Deviation}\delta =i+e-A\\ \text{Here}A={60}^o\end{array}$

$\begin{array}{cc}{r}_1+r_2& =A\\ r_1=r_2& =r\\ r+& r=A\\ & 2r=60\end{array}$

$x={30}^{\circ }$

so option $\left(A\right)$ is correct