Optics Question 825
Question: A triangular prism of glass is inside water. A ray, incident normally, on one of the faces, is totally reflected from face BC. Then the minimum refractive index of glass is -
Options:
A) $ \frac{\sqrt{3}}{2} $
B) $ \frac{5}{3} $
C) $ \frac{2\sqrt{2}}{5} $
D) $ \frac{4\sqrt{2}}{3} $
Show Answer
Answer:
Correct Answer: D
Solution:
[d] For T.I.R. $ 45{}^\circ >C $
$ \therefore \sin 45{}^\circ >sinC $
$ \therefore \frac{1}{\sqrt{2}}>\frac{4/3}{n} $
$ \therefore n>\frac{4\sqrt{2}}{3} $
