There is a small source of light at some depth below the surface of water (refractive index = 4/3) in a tank of large cross-sectional area. Neglecting reflection from the bottom and absorption by water, the percentage of light that emerges out of the surface is nearly: [Use surface area of a spherical cap = 2πrh]
Options

Question

There is a small source of light at some depth below the surface of water (refractive index = 4/3) in a tank of large cross-sectional area. Neglecting reflection from the bottom and absorption by water, the percentage of light that emerges out of the surface is nearly: [Use surface area of a spherical cap = 2πrh]

Options

G1 Physics · Accepted Answer

Derived solution: Step 1: Use Snell’s law at each plane interface. For paraxial viewing through a plane surface, apparent depth = real depth × n(observer)/n(object medium). Step 2: Substitute the values given in the question and apply the geometry/sign convention shown. Step 3: On simplification the result is 17%. Therefore the correct option is A.