Question

A small piece of wood is floating on the surface of a 2.5 m deep lake. Where does the shadow form on the bottom when the sun is just setting? Refractive index of water = 4/3.

Answer 1

Given:

μw= 4/3

lake depth= 2.4m

When sun is rising, θ =90°

sin i/ sin r= μ2/μ1

sin 90/sinr=4/3

1/sinr= 4/3

sinr = 3/4

r= 49°

Thus, x/2.5=tanr= 1.15

x= 2.5 x 1.15

x=2.8m

Answer 2

Height of the lake = 2.5 m