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Homework Help: Angle of incidence question

  1. Nov 8, 2009 #1
    b]1. A light beam coming from an underwater spotlight exits the water at an angle of 68° to the vertical. At what angle of incidence did it hit the air-water interface from below the surface?

    2. snell's law n1sin[tex]\Theta[/tex]1=n2sin[tex]\Theta[/tex]2

    3. sin[tex]\Theta[/tex]1=1.33(sin68)
    After doing this I took the inverse sin of it and it comes up as error on my calculator. I know it should be an easy question but I dont know where I am messing up.
  2. jcsd
  3. Nov 8, 2009 #2


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    Gold Member

    It looks like you've got the equation set up wrong. It should read:

    [tex]n_1\sin{(\theta_1)} = n_2\sin{(\theta_2)}[/tex]

    Where [itex]n_1 = 1.33[/itex], [itex]n_2 = 1[/itex], and [itex]\theta_2 = 68[/itex].
  4. Nov 8, 2009 #3
    I knew it would be something dumb, thanks for your help.
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