Total Reflection in a Stream of Water

When light passes to a new medium, some of the light will refract (bend) and some of it will reflect. The angle of refraction is given by Snell's Law. There exists a critical angle which is the minimum angle at which all light is reflected. At the critical angle, light travels through the plane where the two media meet. In this model, the light will continually reflect through the stream of water creating a total internal reflection. The stream of water get the light through, to the end of the stream. Total internal reflection is the principle behind fiber optics.