Optics Question 974
Question: The refractive index of water is 4 / 3 and that of glass is 5/3. What will be the critical angle for the ray of light entering water from the glass
[RPMT 1996]
Options:
A) $ {{\sin }^{-1}}\frac{4}{5} $
B) $ {{\sin }^{-1}}\frac{5}{4} $
C) $ {{\sin }^{-1}} $
$ \frac{1}{2} $
D) $ {{\sin }^{-1}}\frac{2}{1} $
Show Answer
Answer:
Correct Answer: A
Solution:
$ _{w}{\mu _{g}}=\frac{1}{\sin C}\Rightarrow \frac{{\mu _{g}}}{{\mu _{w}}}=\frac{5/3}{4/3}=\frac{1}{\sin C} $
$ \Rightarrow \sin C=\frac{4}{5}\Rightarrow C={{\sin }^{-1}}( \frac{4}{5} ) $
