Applications of Total Internal Reflection


Total Internal Reflection can be used as a way to make diamonds sparkle and information travel rapidly on light waves through a fiber optic.

diamond animation (3k) The cut of the diamond favors total internal reflection.  Most rays entering the top of the diamond will internally reflect until they reach the top face of the diamond where they exit.  This gives diamonds their bright sparkle.   Notice in this animation that a ray entering the top doesn't exit the diamond until it reaches the top surface.
Fiber Optic Animation(3k) A fiber optic is a glass "hair" which is so thin that once light enters one end, it can never strike the inside walls at less than the critical angle.   The light undergoes total internal reflection each time it strikes the wall.   Only when it reaches the other end is it allowed to exit the fiber.

Fiber optic cables are used to carry telephone and computer communications.  Advantages over electrical wired include:

  1. Fiber optics can carry much more information in a much smaller cable.
  2. No interference from electromagnet fields result in "clearer" connections.
  3. No electrical resistance.
  4. No hazard of electrocution if cable breaks.

1999 Science Joy Wagon