COMEDK Exam 2018 Solved Paper

Refractive index of water =n
Since, fish looks the bird from water (denser medium) to air (rarer medium).
Hence, normal shift d=(n−1)h
But according to question, real depth h=y
∴‌‌d=(n−1)y‌‌(∵ height of bird =y)...(i)
The bird's height from the surface of the water is equal to the summation of the normal shift and height of the bird from the surface.
i.e. d′=y+d=y+(n−1)y [From Eq. (i)]
d′=ny . . . (ii)
Total actual distance between bird and fish
=x+d′=x+ny