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Homework Help: Index of refraction of the plexyglass

  1. May 20, 2004 #1

    Sin(theta r)/Sin(theta i) is reversed from Sin(theta i)/Sin(theta r) = n, what does this mean? I'm quite confused since I'm doing a physics lab, and the class was told to make a graph where we measured angles with polar paper, pins and plexyglass. Could it possibly the index of refraction of air?

    Thanks so much.
  2. jcsd
  3. May 20, 2004 #2

    Doc Al

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    Staff: Mentor

    Snell's law

    That n is the index of refraction of the plexyglass. Here's the explanation. First, Snell's law of refraction is this:
    [tex]n_1 sin\theta_1 = n_2 sin\theta_2[/tex]
    Where 1 and 2 represent the two different media. If you are going from air (1) to plexyglass (2), then you can rewrite this as:
    [tex]sin\theta_i = n_2 sin\theta_r[/tex]
    (Note that the index of refraction of air is n = 1.)
    So... you can solve for the index of refraction of the plexyglass:
    [tex]n_2 = \frac{sin\theta_i}{sin\theta_r}[/tex]
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