Question

A ray of light passes through equilateral prism $(\mu =1.5)$ such that angle of incidence is equal to angle of emergence and the later is equal to $3/4^{th}$ of prism angle. The angle of deviation is : -

• A. ${30}^o$
• B. ${60}^0$
• C. ${45}^o$
• D. ${120}^o$

Answer 1

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

$\begin{array}{c}i+e=A+d\\ i=e=\left(\frac{3}{4}\right)A\\ \left(\frac{3}{4}\right)A+\left(\frac{3}{4}\right)A=A+d\\ 1.5A-A=d\\ d=\frac{A}{2}\\ A={60}^0\left(equilateralprism\right)\\ d={30}^0\end{array}$