Question

A light ray is incident on a prism in minimum deviation position and suffers a deviation of ${34}^o$. If the shaded half of the prism is removed off, then the same ray will suffer a deviation of :

• A. $0^o$
• B. ${65}^o$
• C. ${17}^o$
• D. ${34}^o$

Answer 1

The correct option is C ${17}^o$

For a prism, $\delta =A(\mu -1)$
After removing the half portion, A is reduced to $A/2$.
$\therefore \frac{\delta }{{\delta }^{\prime }}=\frac{A(\mu -1)}{A^{\prime }(\mu -1)}=\frac{A}{A^{\prime }}$
or ${\delta }^{\prime }=\frac{A^{\prime }}{A}\delta =\frac{A}{2A}\times {34}^o=\frac{{34}^o}{2}={17}^o$.