Total Internal Reflection occurs when a ray of light traveling from a denser medium to a less dense medium strikes the boundary at an angle greater than the critical angle. The result of this is the ray of light is reflected back into the denser medium in which it started. A critical angle is the incident angle measured when the refracted ray of light is equal to 90 degrees.

There are many applications of Total Internal Reflection (TIR) apparent in every day life. Some examples of these include Prisms, Periscopes, Binoculars, Optical Fibres and Mirages.

In countries in the Northern Hemisphere many car accidents in Winter are caused by `black ice.' This term does not refer to ice coloured black but ice, which traps light. Inside the ice the rays of light, which enter are totally internally reflected. They never hit the surface at more than the critical...