MIT Physics Demo - Refraction & Total Internal Reflection
A beam of light from a helium-neon laser is directed at a tank of water and is refracted as it enters the water. The outgoing angle of refraction is smaller than the incident angle. Next, the laser is directed from below the water's surface. At a certain critical angle, the beam is totally reflected at the surface, there is no outgoing refracted beam.
MIT Department of Physics Technical Services Group