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Homework Help: Critical Angle Problem

  1. May 17, 2009 #1
    1. The problem statement, all variables and given/known data
    The critical angle for a special glass in air is 44 degrees. What is the critical angle if the glass is immersed in water?

    2. Relevant equations
    sin(critical angle) = 1/index of refraction

    index of refraction of air is 1.00
    index of refraction of water is 1.333

    3. The attempt at a solution
    I have no clue where to start that's the problem :S.

    Just for reference, the textbook answer is 68 degrees.

  2. jcsd
  3. May 17, 2009 #2

    Doc Al

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    Staff: Mentor

    Hint: That's only true if the surrounding medium has n = 1. (How is the critical angle formula derived?)
  4. May 17, 2009 #3
    Ah, Snell's Law where [tex]\theta_2[/tex] = [tex]90^\circ[/tex].

    Last edited: May 17, 2009
  5. Jun 19, 2009 #4
    Have you tried using the eqaution n1sinQ=n2sinQ
    by the way the one is just saying its the first refractive index, and the Q is theta.
    Maybe you could try this eqaution.
    Thanks I hope that helps... :cool:

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