Question

Find the net deviation produced in the incident ray for the optical instrument shown in figure below. (Take refractive index of the prism material as $2$).

• A. ${66}^{\circ }CW$
• B. ${66}^{\circ }ACW$
• C. ${54}^{\circ }ACW$
• D. ${54}^{\circ }CW$

Answer 1

The correct option is D ${54}^{\circ }CW$

Deviation produced by the mirror is
${\delta }_1=\pi -2\times 60={60}^{\circ }CW$
Deviation produced by the prism is
${\delta }_1=(1-2)\times 6=6^{\circ }ACW$
So, net deviation, $\delta =\delta +{\delta }_2$
$=({60}^{\circ }-6^{\circ })CW={54}^{\circ }CW$.