Optics Question 965
Question: If the critical angle for total internal reflection from a medium to vacuum is $ 30{}^\circ $ , the velocity of light in the medium is
[CPMT 1972; MH CET 2000; KCET 2000; BCECE 2003; RPMT 2003]
Options:
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
Show Answer
Answer:
Correct Answer: B
Solution:
$ \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 $
