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Homework Help: Grating, second-order spectrum and interference

  1. Dec 3, 2008 #1
    1. The problem statement, all variables and given/known data
    What is the minimum number of lines per centimeter that a grating must have if there is to be no second-order spectrum for any visible wavelength? (Let visible region extend from 400 nm to 570 nm.) Hint: Draw a diagram showing the relative positions of the rays corresponding to the first-order blue spectrum, the first order red spectrum, and the edge of the second-order spectrum.

    2. Relevant equations
    dsin(theta) = m(lambda)

    3. The attempt at a solution
  2. jcsd
  3. Apr 7, 2009 #2
    did you ever find a solution to this?
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