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Homework Help: Light through slits

  1. Aug 12, 2004 #1
    Almost done guys :)

    If the first order bright lines formed by two slits at a distance of 2 meters are 3 cm apart, find the wavelength of the light if the slit seperation is 9.12x10^-3 cm.

    So, to find the wavelength, this is what I did.

    wavelength = 9.12 * 10^-5m * (2m/(3*10^-2m)) = .00608m.

    i'm not understanding what i am doing wrong. any input would be helpful. Thanks!
     
  2. jcsd
  3. Aug 12, 2004 #2

    Doc Al

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    Staff: Mentor

    You need to understand the formula for the double slit diffraction pattern. The distance of the first maxima (from the central maxima) is given by:
    [tex]y = \frac{\lambda L}{d}[/tex]
     
  4. Aug 12, 2004 #3

    right, so y=9.12*10^-5m, d = 2m and L = 3*10^-2m.
     
  5. Aug 12, 2004 #4

    Doc Al

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    Staff: Mentor

    Nope:
    L is the distance to the screen
    d is the distance between the slits
    y is the distance of the first maxima to the center (this is half of the distance between those maxima).
     
  6. Aug 13, 2004 #5
    thanks, i got it :)
     
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