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Homework Help: How Thick Is The Foil

  1. Apr 30, 2013 #1
    1. The problem statement, all variables and given/known data
    A fine metal foil separates one end of two pieces of optically flat glass, as in Figure 24-33 in the textbook. When light of wavelength 700nm is incident normally, 24 dark lines are observed (with one at each end).

    How thick is the foil?

    2. Relevant equations
    t = mλ, m = 0,1,2,...

    3. The attempt at a solution
    because m = 0 corresponds to the edge where the glasses touch m+1 represents the number of the fringe so the thickness of the foil is

    d = (1/2)(23)(700nm)
    d = 8.05 * 10 ^ -6 this is not the right answer and i dont understand why where am i going wrong
    Last edited: Apr 30, 2013
  2. jcsd
  3. Apr 30, 2013 #2
    what are the units of your answer?
  4. Apr 30, 2013 #3
    the answer i keep getting is 8.05 * 10^-6 which i guesss would be a micrometer ( i edited that above) which i guess would be but the answer has to be in meters.
  5. Apr 30, 2013 #4
    I think you are correct.
  6. Apr 30, 2013 #5
    wow yeah, the problem was i wasnt putting in the *10^-6.... thanks for your help stupid mistake on my part.
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