Q124 / 160 · WBJEE 2010 · Physics
The radius of the light circle observed by a fish at a depth of 12 meter is (refractive index of water $=4 / 3$ )
- A$36 \sqrt{7}$
- Correct answerB$\frac{36}{\sqrt{7}}$
- C$36 \sqrt{5}$
- D$4 \sqrt{5}$
Solution
$$
\text { Hints : } r=\frac{h}{\sqrt{\mu^2-1}}=\frac{12}{\sqrt{\frac{16}{9}-1}}=\frac{12 \times 3}{\sqrt{7}}=\frac{36}{\sqrt{7}}
$$
Hence, the correct answer is option: 'B'.