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

Homework Help: Optics: Beams through a Prism

  1. Dec 14, 2011 #1
    My big problem here is with the geometry....
    1. The problem statement, all variables and given/known data
    I just took a picture of the problem. It's 15-10.
    http://img839.imageshack.us/img839/9712/optics.jpg [Broken]

    2. Relevant equations
    [tex]n_1sin\theta_1=n_2sin\theta_2[/tex]
    [tex]n_{\bot}=1.6584[/tex]
    [tex]n_{Parallel}=1.4864[/tex] (I can't find the Parallel sign)

    3. The attempt at a solution
    So the prism is a birefringent material. The beam of light which oscillates in and out of the page is perpendicular to the optical axis and is going into a medium in which it will be parallel, so to find the angle of refraction..
    [tex]1.6584sin(45°)=1.4864sin\theta_{r1}
    This gives an angle of refraction of 52.1°. Doing the opposite with the other beam of light gives an angle of 39.33°.

    So for the first part, their angle of deviation is about 13°. The problem is, I cannot determine the angles in which the beams hit the other wall of the prism. Every time I think I get it, the bottom angle has an angle greater than its critical angle so total internal reflection would happen. This isn't the case from the picture so I must be doing something wrong. How would I get the angles in which the light hits the walls?

    Thanks!
     
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Dec 14, 2011 #2

    Delphi51

    User Avatar
    Homework Helper

    Like this? I worked my way around the triangle from the beam entry to its exit from the prism.
    prism.jpg
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook