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Homework Help: Question on a Double Split Problem

  1. Jan 17, 2007 #1
    1. Two slits are 0.153 mm apart. A mixture of red light (wavelength = 665 nm) and yellow-green light (wavelength = 565 nm) falls on the slits. A flat observation screen is located 2.17 m away. What is the distance on the screen between the third-order red fringe and the third-order yellow-green fringe?

    d= 0.153mm = 1.53 x 10^-3m
    red wavelength= 665 nm = 6.65 x 10 ^-7 m
    Yellow-green wavelength = 565 nm = 5.65 x 10^-7 m
    x = 2.17m
    m = 3




    2. Sin theta = m (wavelength/d)



    3. red:
    Sin Theta = 3(6.65 x 10^-7) / (1.53 x 10^-3) = 0.0013m
    Tan Theta = 0.0013 = y/x = y/2.17
    red y= 0.00283

    yellow-green:
    Sin theta = 3 (5.65 x 10^-7) / (1.53 x 10^-3) = 0.0011
    Tan theta = 0.0011 = y/x = y/2.17
    yellow-green y= 0.0024


    red y - yellowgreen y = .00283 - .0024 = 0.00043



    This is not right for some reason.
    What am I doing wrong?
     
  2. jcsd
  3. Jan 17, 2007 #2
    ok the answer was .0043, but I don't see where the decimal is wrong...
     
  4. Jan 17, 2007 #3
    ok got it, nevermind.
     
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