Q. If the critical angle for total internal reflection from a medium to vacuum is $30{^\circ}$, the velocity of light in the medium is
A) $3 \times 10^{8}\ m/s$
B) $1.5 \times 10^{8}\ m/s$
C) $6 \times 10^{8}\ m/s$
D) $\sqrt{3} \times 10^{8}\ m/s$
Explanation
(b) $\mu = \frac{1}{\sin C} = \frac{1}{\sin 30} = 2$
$\therefore v = \frac{3 \times 10^{8}}{2} = 1.5 \times 10^{8}m/s$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.