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Homework Help: The lines in a grating are uniformly spaced at

  1. Feb 23, 2012 #1
    1. The problem statement, all variables and given/known data

    The lines in a grating are uniformly spaced at 1530 nm. Calculate the angular separation of the second order bright fringes between light of wavelength 600 nm and 603.11 nm. Answer in __mrad

    2. Relevant equations

    Theta = sin-1 ((m*lambda*2)/(d))

    3. The attempt at a solution

    d = 1530 nm
    m = 2
    lambda1 = 600 nm
    lambda2 = 603.11

    Theta1 = sin-1 ((2*600)/(1530))
    = 51.66

    Theta2 = sin-1 ((2*603.11)/(1530))
    = 52.03

    Theta2 - Theta1 = (52.03)-(51.66) = 0.37

    The answer is apparently wrong. Please help! I would really appreciate it. Thanks!
  2. jcsd
  3. Feb 24, 2012 #2


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    Homework Helper

    Hi AnnieMoo,

    In what units have you got the separation angle? And what is said in the problem text?

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