Physics · Ray Optics

There is a small source of light at some depth below the surface of water (refractive index = 43) in a tank of large cross-sectional surface area. Neglecting any reflection from the bottom and absorption by water, the percentage of light that emerges out of the surface is nearly: [Use the fact that the surface area of a spherical cap of h eight h and radius of curvature r is 2πrh]