A ray of sunlight hits a frozen lake at a 45° angle of incidence. At what angle of refraction does the ray penetrate the ice? At what angle does it penetrate the water beneath the ice?
Angle of refraction at the air-ice interface
Angle of refraction at the ice-water interface
Using the following refractive indices
Using Snell's Law of refraction applicable for a ray crossing the interface between two media which have refractive indices
For first interface when ray enters from air to ice
Due to geometry this becomes angle of incidence for the second interface as ray enters from ice to water. Using Snell's law again we have