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Homework Help: Optics question- please reply

  1. Jul 29, 2005 #1
    Optics question-- please reply ASAP

    A person stands against a thick plate of glass, n=1.5. everything on the other side of the glass plate is inside of a circle of radius = 1 meter.
    wavelength air = 600 x 10 ^ -9 meters
    wavelength of glass = 4 x 10 ^ -7 meters
    Critical angle of glass plate = 41.8ยบ

    HOW THICK IS THE GLASS PLATE?
     
    Last edited: Jul 29, 2005
  2. jcsd
  3. Jul 29, 2005 #2
    This problem is pooly formulated and posted.

    Glass doesn't have a wavelength, and how far is the person from the glass?

    If my eyeball doesn't touch the glass then I will see all the way to infinity, not
    just to a 1 meter radius. My eyeball would have to be in fluid contact with the
    window in order for there to be a point of total internal reflection which is visible
    to me.

    That having been said, the glass plate would be 381 Inches thick.
     
  4. Jul 31, 2005 #3

    Doc Al

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    Staff: Mentor

    I agree that the problem is not clearly stated. I interpret it this way: looking at the person's image from the other side of the glass, every point is only visible inside a circle of radius 1 meter. With this interpretation, the problem is solvable. (The wavelengths are irrelevant.)
     
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