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Homework Help: Double-slit Interference

  1. Feb 19, 2012 #1
    1. The problem statement, all variables and given/known data

    A double-slit interference pattern is created by two narrow slits spaced 0.21mm apart. The distance between the first and the fifth minimum on a screen 60cm behind the slits is 6.2mm. What is the wavelength of the light used in this experiment?

    2. Relevant equations

    gamma = d/L * Delta y

    3. The attempt at a solution

    delta y = 6.2mm/5 = 1.24*10 ^-3m
    gamma = d/L delta y
    = (2.1*10^-4m)/0.6m * 1.24*10^-3
    = 434nm
    but this is incorrect. Where did I go wrong?
  2. jcsd
  3. Feb 19, 2012 #2


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    If the 6.2 mm was the distance between the first and second minima, would you say the distance between the minima is Δy = 6.2 mm/2?
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