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Homework Help: Light intensity through a slit

  1. Apr 27, 2014 #1
    1. The problem statement, all variables and given/known data
    After a laser beam passes through two thin parallel slits, the first completely dark fringes occur at ±14.0∘ with the original direction of the beam, as viewed on a screen far from the slits.

    A)What is the ratio of the distance between the slits to the wavelength of the light illuminating the slits?
    d/lambda = 2.07

    B)What is the smallest positive angle, relative to the original direction of the laser beam, at which the intensity of the light is 110 the maximum intensity on the screen?


    2. Relevant equations

    I = Iocos2(ø/2)

    ø = 2∏dsinθ/λ

    3. The attempt at a solution

    so for this I solved for phi and then substituted that into the second equation and for this sinθ is ≈θ I just solved for theta in the 2nd equation

    for ø= 2cos-1(√(1/10))

    then ø/(2∏(d/λ)) = Θ

    for Θ I got .192 but I cant figure out what I did wrong

    thank you in advance
  2. jcsd
  3. Apr 27, 2014 #2

    Simon Bridge

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    I'm getting the same as you.
    Are you expected to give your answer in degrees or radiens?
  4. Apr 28, 2014 #3
    radians is what we were told to do for all of these problems
  5. Apr 28, 2014 #4

    Simon Bridge

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    What leads you to believe that you've done anything wrong then?
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