1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Diffraction grating problem, missing orders, diffraction minimum and maximums.

  1. Mar 12, 2009 #1
    1. The problem statement, all variables and given/known data
    Missing orders occur for a diffraction grating when a diffraction minimum coincides with an interference maximum. Let D be the width of each slit and d the separation of slits. (a) show that if d = 2D, all even orders (m=2,4,6) are missing. (b) show that there will be missing orders whever d/D = m1/m2. where m1 and m2 are integers. (c) Discuss the case d + D, the limit in which the space between slits becomes negligible.

    2. Relevant equations
    sin(theta) = m(lamda)/d

    3. The attempt at a solution
    I figured out that in order for there to be a missing order m1 and m2 needs to coincide. However, setting m1D=m2d (m2 can't be 0), plugging in the given information d=2D, I simply get m2=m1/2. That did not seem to prove anything. Please give me some hints.
  2. jcsd
  3. Mar 13, 2009 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    You'll need to use the equation for diffraction from a single slit also.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook