1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
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: A shaft of light pass through the prism

  1. Mar 11, 2006 #1
    A shaft of light passes through a prism with refracting angle [tex] \theta [/tex] and refractive index [tex] n [/tex]. Let [tex] \alpha [/tex] be the deviation angle of the shaft. Demonstrate that if the shaft of light passes through the prism symetrically the angle [tex] \alpha [/tex] is the least?
  2. jcsd
  3. Mar 11, 2006 #2
    The least in regards to what?

  4. Mar 11, 2006 #3

    I suppose that [tex] \beta [/tex] is the refracting angle

    I think that it try to proove that [tex]\beta[/tex] is equal to [tex] \theta [/tex] angle [tex] \alpha [/tex] will become the least.

    Attached Files:

  5. Mar 12, 2006 #4


    User Avatar
    Homework Helper

    "passes through symmetrically" means that the path inside the prism
    is parallel to the face of the prism that isn't used as a window ...
    that is, theta_glass on face 2 = - theta_glass on face 1.

    You'll probably want to assume an "apex" angle for the prism
    and recall that the interior angles in a triangle sum to 180,
    to relate the theta_glass on face 2 to the theta_glass on face 1.

    With the deflection angle as a function of theta_glass, set the derivitive =0.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook