Q. A ray falls on a prism $ABC\ (AB\ = \ BC)$ and travels as shown in figure. The minimum refractive of the prism material should be
A) $\frac{4}{3}$
B) $\sqrt{2}$
C) 1.5
D) $\sqrt{3}$
Explanation
(b) For total internal reflection to take place
$i > \ \theta c$
Taking sine on both sides, we get
$\sin i > \sin{\theta c}$
[as angle i at both face will be 45${^\circ}$]
$\Longrightarrow \frac{1}{\sqrt{2}} > \frac{1}{\mu}$
$\Longrightarrow \mu > \sqrt{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.