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Homework Help: Finding Longest Wavelength

  1. Nov 4, 2015 #1
    1. The problem statement, all variables and given/known data
    A sheet of glass (nglass = 1.5) is coated with a 95.6-nm-thick layer of magnesium fluoride (ncoating = 1.38) to prevent reflection in the visible spectrum. Assume the incoming light is normal to the surface.
    What is the longest wavelength of light strongly reflected from this coated surface?

    2. Relevant equations

    3. The attempt at a solution

    95.6 = x/4(1.38) = 527 nm
    This is incorrect however.
  2. jcsd
  3. Nov 6, 2015 #2

    Simon Bridge

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    Homework Helper

    Please show your reasoning.
    Note: you have written 95.6 = 527 ... which is, indeed, false. I don't think that is what you meant.

    Under what circumstances does a reflected wave invert?
    What condition is needed for strong reflection off the top surface of the film?
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