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Homework Help: Diffraction equation

  1. Sep 20, 2008 #1
    1. The problem statement, all variables and given/known data
    I have to find "sinθ" and "d" in the diffraction equation.

    2. Relevant equations
    The formula is n(lambda) = d(sinθ)
    I have the n, length, width, and hypotenuse.
    n=1, L=335 W=42.5 hyp=337.8

    3. The attempt at a solution
    I forgot how to get the angle for sin. So i'm pretty much stuck.
  2. jcsd
  3. Sep 20, 2008 #2


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    Welcome to PF!

    Hi magma_saber! Welcome to PF! :smile:

    Do you mean that if you have, say sinθ = x, you want to get θ as a function of x?

    If so, the solution is θ = sin-1x (also written arcsin(x)), which most electronic calculators will do … alternatively, use sine tables "backwards"! :wink:

    Or am I misunderstanding the problem? :confused:
  4. Sep 21, 2008 #3
    I got sinθ. In my book it says sinθ = opposite over hypotenuse. By doing that i got 42.5/337.8. so sinθ should equal 0.126 right?
    Now how do i get "d"? The equation is (n)(lambda)=(d)(sinθ). lambda is 650 btw.
    So would this be the equation?
  5. Sep 23, 2008 #4
  6. Sep 23, 2008 #5


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    Hi magma_saber! :smile:

    I think people have been avoiding answering because you haven't made it clear what W and d are. :confused:

    If the correct equation is (n)(lambda)=(d)(sinθ), and if W and hyp are the correct opposite and hypotenuse, then 650 = d times 0.126. :smile:

    (not sin(0.126) … 0.126 is the sin :wink:)
  7. Sep 23, 2008 #6
    thanks i got it now.
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