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Single Slit Diffraction

  1. Apr 22, 2015 #1
    1. The problem statement, all variables and given/known data

    A single slit illuminated by light of wavelength λ = 610 nm produces a diffraction pattern with its first minimum at 3.5 mm from the central maximum. (a) Find the slit width, and (b) For the same slit, what wavelength of light would produce a first minimum at θ = 4.0 degrees.

    2. Relevant equations

    D = slit width
    m = minima order
    L = distance from the slit to the wall

    D sin θ = m λ
    tan θ = sin θ = θ (small angle approximation)

    3. The attempt at a solution

    λ = 610 nm or 6.1 x 10^-7 m
    m = 1 (first order minima)
    x = 3.5 mm (which is the distance from the central maximum to the first minimum)

    tan θ = x / L

    D = m λ / sin θ

    I would be able to solve this question if I was given either the distance from the slit to the wall (L) or the angle (θ), however, I am not given any of this, and as such, I am unsure how to proceed.
  2. jcsd
  3. Apr 23, 2015 #2

    Simon Bridge

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    Science Advisor
    Homework Helper

    It is not possible to solve the problem with the information written above.
    You should complain to the person who set the problem - make sure you have read all the information given as sometimes a vital bit is someplace else. Check with other people doing the same problem - it helps to have others also complaining.
  4. Apr 23, 2015 #3
    Hello David,

    Please update us if the professor says it was right and then shows you how to do it. I've been thinking about this question for a bit but have not come up with a solution for you. I agree with Simon, I do not believe it can be solved as presented. But I will think about it more if I have time later this week. Please keep us updated. In the mean time don't get too caught up on it. Move on to other problems. :D

    Best Regards,

    Caleb P.
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