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Unpolrized light passes through 2 polarizers

  1. Apr 19, 2009 #1
    1. The problem statement, all variables and given/known data
    Unpolarized light passes through two polarizers whose transmission axes are at an angle of 28.1° with respect to each other. What fraction of the incident intensity is transmitted through the polarizers?


    2. Relevant equations
    I=.5xIoxcos^2(theta)


    3. The attempt at a solution
    Im pretty sure that i have the correct equation, but i'm confused because in the problem I am not given an Incident Intensity, therefore how can i solve for the transmitted intensity? If someone could please start me in the right direction, i would appreciate it very much!
     
  2. jcsd
  3. Apr 20, 2009 #2

    alphysicist

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    Hi Cheezay,

    They are not asking for the transmitted intensity, they are asking for the fraction of the incident intensity that is transmitted, which is the ratio of transmitted intensity to incident intensity. Do you see how to solve for that?
     
  4. Apr 20, 2009 #3
    No, i'm sorry i don't see how to solve for that. I thought maybe it might be 1/2 the incident intensity, but that answer is not correct.
     
  5. Apr 20, 2009 #4

    alphysicist

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    The ratio you're looking for is:

    (transmitted intensity) / (incident intensity) = I / Io

    Using your equation (from your first post), what is that quantity equal to?
     
  6. Apr 21, 2009 #5
    Then I/Io= .5 x cos^2(theta). Thanks so much for the help!
     
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