Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Spherical glass object with index of refraction N

  1. Nov 15, 2005 #1
    imagine there is a spherical glass object with index of refraction N
    is that possible that for some N and angle of incidence A, the light will be total internal reflected forever. In other word, the light will travel within the object forever?
    i have been trying to proof it. but i dont know much about optic.... so no where to start at
    Last edited: Nov 15, 2005
  2. jcsd
  3. Nov 15, 2005 #2


    User Avatar

    Staff: Mentor

    What you are describing is the operating principle behind fiber optic communications.
  4. Nov 15, 2005 #3


    User Avatar

    Staff: Mentor

    For a cylindrical object with light coming in one end, yeah... but for a spherical object there's no incident angle that causes the light to be trapped permanantly inside.

    Leon, all you need for this is Snell's Law for refraction of a light ray, and a bit of geometry. Note that the angle of the ray after the first refraction (entering the sphere) has a certain maximum value, no matter what the incident angle is. That would be a good starting point for a proof.
    Last edited: Nov 15, 2005
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Spherical glass object with index of refraction N
  1. Refractive index (Replies: 11)

  2. Refractive index (Replies: 2)

  3. Refractive index (Replies: 5)

  4. Index of refraction (Replies: 3)