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Homework Help: Diffraction of Light through Single Slit

  1. Dec 18, 2006 #1
    1. The problem statement, all variables and given/known data

    Monochromatic light falls into slit 3.00*10^-6 wide. The angle between the first dark fringes on either side of the cental maximum is 25 derees. Calculate the λ.

    w=3.00*10^-6 m
    ө=25˚

    2. Relevant equations

    sin(ө) = nλ/w
    sin(ө) = ((m+0.5)λ)/w
    Δy=λL/w

    3. The attempt at a solution

    sinө=λ/w
    λ=sin25*3.0*10^-6
    =1.3*10^-6 m

    hoever the answer is 6.49*10^-7
     
  2. jcsd
  3. Dec 18, 2006 #2
    Please help its really easy I just don't get the concept!
     
  4. Dec 18, 2006 #3

    Doc Al

    User Avatar

    Staff: Mentor

    You have misinterpreted the angle. You are given the angle between the first dark fringes, but in the equation sin(theta) = n lambda/w, theta is the angle of the dark fringes measured from the central maximum.
     
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