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Diffraction Grating Maximum Order

  1. May 24, 2010 #1
    1. The problem statement, all variables and given/known data

    A grating having 1000 lines per mm is illuminated with sodium light of mean wavelength 589.3 nm. Determine the maximum order of diffraction that can be observed.

    2. Relevant equations

    dsin([tex]\theta[/tex])=m[tex]\lambda[/tex]

    d=slit spacing

    3. The attempt at a solution

    The order of diffraction is given by m, and m=(dsin[tex]\theta[/tex])/[tex]\lambda[/tex], so i figure m takes a maximum value when sin([tex]\theta[/tex])=1, or when m=d/[tex]\lambda[/tex] but i am not sure if this is correct.
    I'd be grateful for any hints.
     
    Last edited: May 24, 2010
  2. jcsd
  3. May 24, 2010 #2
    Yes, the angle can't be greater than 90 degrees.
    So if you put sin = 1 you will get a value for m that could be, for example, 3.4
    This means you could get a 3rd order but not a 4th
     
  4. May 24, 2010 #3
    thanks
     
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