110. Total Internal Reflection

  1. Beams on blackboard - total internal reflection is shown well with the blackboard optics prism piece. As you rotate the prism shown above counter-clockwise, the refracted beam will become parallel to the hypotenuse; at this point the reflected beam becomes much brighter and the refracted beam disappears. You can use your value for the index of refraction from Blackboard Optics to check against the critical angle.
  2. Laser beam in aquarium - a horizontal laser beam in an aquarium of water is reflected towards the surface with a small mirror. You can show the angle at which the beam penetrates the surface and the angles for which it is totally reflected.
  3. Pieces of bent lucite rods and sections of fiber optics bundles are available to show the bending of light through light pipes.
  4. The water stream laser light-pipe is an impressive demonstration of light totally internally reflecting in a flowing stream of water.