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Homework Help: How many lines per centimeter does the grating have?

  1. Mar 20, 2008 #1
    1. The problem statement, all variables and given/known data

    The light shining on a diffraction grating has a wavelength of 488 nm (in vacuum). The grating produces a second-order bright fringe whose position is defined by an angle of 8.02°. How many lines per centimeter does the grating have?

    2. Relevant equations

    d sin q = nl

    3. The attempt at a solution

    d = (2)(488)/sin(8.02) = 6995.474955

    d = 1/N

    N = 1/d = 1/6995.474955 =1.429495505X10^-4 (per M) X 100 = 0.014294955

    It got this answer and it is wrong, I have no idea where to go from here or what to do and would be grateful of any help, thanks!
  2. jcsd
  3. Mar 20, 2008 #2


    User Avatar
    Homework Helper

    You should convert the wavelength from nanometers to meters (or cm, whatever). I don't think you did that properly.
    Last edited: Mar 20, 2008
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