Optics Question 990
Question: A fish looking up through the water sees the outside world contained in a circular horizon. If the refractive index of water is $ \frac{4}{3} $ and the fish is 12 cm below the surface, the radius of this circle in cm is
[NCERT 1980; KCET 2002; AIEEE 2005; CPMT 2005]
Options:
A) $ 36\sqrt{5} $
B) $ 4\sqrt{5} $
C) $ 36\sqrt{7} $
D) $ 36/\sqrt{7} $
Show Answer
Answer:
Correct Answer: D
Solution:
$ r=\frac{3h}{\sqrt{7}}=\frac{3\times 12}{\sqrt{7}}=\frac{36}{\sqrt{7}} $ .
