A fish lies at the bottom of a 4m deep water lake. A bird flies 6m above the water surface. Then the distance between (μ of water is 4/3)
A. Bird and image of fish is 9m
B. Fish and image of bird is 12m
C. Fish and image of bird is 8m
D. Fish and image of bird is 10m

Hint: Find image of the fish and then analyse the option carefully.

Formula: $\mu = \dfrac{{Real{\text{ }}depth}}{{Apparent{\text{ }}depth}}$

Complete step by step solution:

Given μ(water) = $\dfrac{4}{3}$
For fish:
$\mu = \dfrac{{Real{\text{ }}depth}}{{Apparent{\text{ }}depth}}$
Apparent depth = Real depth $\times$ $\dfrac{1}{\mu } = 4 \times \dfrac{3}{4} = 3$
For a bird, fish appears 3m below the water surface.
Distance between bird is not equal to Image of fish = 6+3=9m

Thus the correct answer is Solution: A. Bird and image of fish is 9m

Note: Real Depth is actual distance of an object beneath the surface, as would be measured by submerging a perfect ruler along with it.