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Homework Help: Glass wedge

  1. Apr 18, 2010 #1
    1. The problem statement, all variables and given/known data
    It's not a specific question. It's more of a general knowledge. As you know, an air wedge forms when two glass plates have one ends meeting each other and the other ends opening up.
    Here's the diagram: http://1.bp.blogspot.com/_g3mLW-twYGc/R-EDX7CqirI/AAAAAAAAALc/v7csfR3s8Vc/s400/wedge1.bmp

    And in this air wedge, a dark spot forms at the edge due to destructive interference.

    But, what happens if the wedge is reversed? So instead of having two glass plates, what if there is a glass wedge with "air plates"?
    Would the pattern be inverted?

    2. Relevant equations
    constructive 2t = (m+1/2) lambda
    destructive 2t = (m) lambda

    3. The attempt at a solution
    I think the pattern will be the same because there is another destructive interference (a phase difference of pi) at the edge. Correct me if I am wrong.
  2. jcsd
  3. Apr 19, 2010 #2


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    Homework Helper

    " Relevant equations
    constructive 2t = (m+1/2) lambda
    destructive 2t = (m) lambda"

    If the wedge is made from a medium of refractive index N, the equations will hold for N*t instead of t.

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