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Homework Help: Double slit interference pattern

  1. Aug 19, 2010 #1
    1. The problem statement, all variables and given/known data

    Two slits are separated by 0.320 mm. A beam of 500-nm light strikes the slits, producing an interference pattern. Determine the number of maxima observed in the angular range -30 degrees < theta < 30 degrees.

    2. Relevant equations

    d*sin(theta) = m*(lambda)

    3. The attempt at a solution

    (.32)sin(30)/.0005mm = m

    so there are 320 maxima in 30 degrees. and thus 640 in this total range. is that right?
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Aug 19, 2010 #2
    Seems fine to me.
  4. Aug 19, 2010 #3
    There is a problem.
    What if it's from -0.001 degrees to 0.001 degrees? Find m corresponding to that case and you will find out what you missed :wink:
  5. Aug 19, 2010 #4
    I think your comment has weight...but the range of visibility of this diffraction pattern are already set in place...namely between 30 and -30 degrees. OP, correct me if I'm mistaken in my interpretation of your problem statement, please.
  6. Aug 20, 2010 #5
    I'm not entirely sure what you are getting at. But, I'm pretty sure it is meant to be strictly limited to 30 and -30.
  7. Aug 20, 2010 #6
    No, I mean, what if the question asks for the number of maxima in another range. Just replace -30 with -0.001 and 30 with 0.001, solve the problem again, and you will see why.
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