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Help with a diffraction grating problem

  1. Mar 18, 2010 #1
    1. The problem statement, all variables and given/known data
    Monochromatic light illuminates a diffraction grating having 5950 lines/cm. The diffraction angle for the first order image is 18 degrees. what is the wavelength in nm

    2. Relevant equations
    wavelength=D * Sin(Theta

    3. The attempt at a solution

    So I know theta is 18, and the D is cm over lines so you have to flip 5950 to 1/5950. What I dont know is does this need to be in nm, or can you leave it in cm. Please explain how to do this for me. Thanks in advance
  2. jcsd
  3. Mar 19, 2010 #2

    Doc Al

    User Avatar

    Staff: Mentor

    All distances had better be in the same units. Since you want the wavelength in nm, express D in terms of nm. 1 cm = 10-2 m; 1 nm = 10-9 m. So 1 cm equals how many nm?
  4. Mar 27, 2010 #3
    Have you access to the answer
    is it 0.520nm?
  5. Mar 27, 2010 #4
    Actually it would be right even if you divide the answer of 1/5950 by hundred to get d in meters then convert the answer to nm
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