Question

A bird in air looks at a fish vertically below it and inside water, h₁ is the height of the bird above the surface of water and h₂, the depth of the fish below the surface of water. If refractive index of water with respect to air be n, then what is the distance of the fish observed by the bird ?

(A) n₁h₁ + nh₂

(B) nh₁ + h₂

(C) h₁ + (h₂ / n)  

(D) h₁ + h₂

Answer 1

The correct option is  (C) h₁ + (h₂ / n).

Explanation:

 Height of bird = h₁

Height of fish = h₂

Now,

[(real depth) / (apparent depth)] = n hence apparent depth = (h₂ / n) 

∴ Distance of fish as observed by the bird is = h₁ + apparent depth = h₁ + (h₂ / n).