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Homework Help: Interference of Light

  1. Apr 11, 2004 #1
    Dear all,

    the question is ...
    Two flat glass plates touch at one edge and are separated at the other edge by a spacer. Using vertical viewing and light is 589 nm(wavelength), five dark fringes(D) are obtained from edge to edge. What is the thickness of the spacer ??

    i know that the thinkness of space(T) = m(1/2wavelength), but
    would u mind to give me some idea for what is the m ?? is 4 or 5 ??

    I think it is 5.....but i checked the correct answer is 4 ?? why ?? because of 'from edge to edge' ??

    best regards and thanks

  2. jcsd
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