Q. A prism having an apex angle $4{^\circ}$ and refraction index 1.5 is located in front of a vertical plane mirror as shown in figure. Through what total angle is the ray deviated after reflection from the mirror
A) $176{^\circ}$
B) $4{^\circ}$
C) $178{^\circ}$
D) $2{^\circ}$
Explanation
(c) $\delta_{\Pr{ism}} = (\mu - 1)A = (1.5 - 1)4{^\circ} = 2{^\circ}$
$\therefore\ \delta_{Total} = \delta_{\Pr{ism}} + \delta_{Mirror}$
$= (\mu - 1)A + (180 - 20) = 2{^\circ} + (180 - 2 \times 2) = 178{^\circ}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.