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Physics Question about Diffraction Gradings

  1. Apr 22, 2012 #1
    What is the highest order of interference maximum that can occur when monochromatic light with a wavelength of 560 nm illuminates a diffraction grating with 4000 lines/cm?

    I thought this seemed really easy, but my answer was incorrect.
    Since there are 4000 lines per centimeter - I solved for the distance between two slits to be 2.5*10^-6 meters.
    Using I=mλ/d and m=1 to to achieve the max I got 0.224 but that was incorrect

    I think I've made a silly error but I'm not sure what it is - can someone point me in a direction
  2. jcsd
  3. Apr 22, 2012 #2
    The max number of orders is d/λ which must be rounded down if it is not a whole number
  4. Apr 22, 2012 #3
    Thank you!
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