Q. A triangular prism of glass is shown in the figure. A ray incident normally to one face is totally reflected, if $\theta = 5{^\circ}$. The index of refraction of glass is
A) Less than 1.41
B) Equal to 1.41
C) Greater than 1.41
D) None of the above
Explanation
(c) For total internal reflection $\theta > C$
$\Rightarrow \sin\theta > \sin C \Rightarrow \sin\theta > \frac{1}{\mu}$
or $\mu > \frac{1}{\sin\theta} \Rightarrow \mu > \frac{1}{\sin{45{^\circ}}} \Rightarrow \mu > \sqrt{2} \Rightarrow \mu > 1.41$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.