WBJEE · Physics · Ray Optics
When a convex lens is placed above an empty tank, the image of a mark at the bottom of the tank, which is 45 cm
from the lens is formed 36 cm above the lens. When a liquid is poured in the tank to a depth of 40 cm, the distance
of the image of the mark above the lens is 48 cm. The refractive index of the liquid is
- A 1.358
- B 1.544
- C 1.472
- D 1.366
Answer & Solution
Correct Answer
(D) 1.366
Step-by-step Solution
Detailed explanation
Initially without water, \(\frac{1}{36}-\frac{1}{-45}=\frac{1}{f} \Rightarrow f=20\) then, after pouring water upto 40 cm apparent object distance \(=\frac{40}{\mu}+5, \frac{1}{48}+\frac{1}{\frac{40}{\mu}+5}=\frac{1}{20} \Rightarrow \mu=1.366\)
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