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Homework Help: Optics problem

  1. Dec 14, 2005 #1
    Hi, I would need help with this problem.

    A beam of light (628 nm) passes through 2 parallel slits in a screen, forming a pattern in which the interfringe is equal to 0,5 cm. If the distance between the slit and the screen is equal to 2,4 m, what is the distance between the slits?

    The answer is 0,3 mm but I always get 1,5 which is way too high:mad:
    I don't really understand how to use the interfringe value...
  2. jcsd
  3. Dec 14, 2005 #2


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  4. Dec 15, 2005 #3
    The dsitance between the slits will be same as one fringe width iin case of perfect interference but may deviate in case of enchanced diffraction effects in interference .

  5. Dec 15, 2005 #4


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    The difference in path length between the two contributions
    occurs right at the slits ... d sin (theta) , where theta is the deflection angle.
    for the "most constructive" interference, the path length difference is an integer wavelength.
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