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Homework Help: SAT II physics light question

  1. Jun 1, 2008 #1
    1. The problem statement, all variables and given/known data
    When monochromatic light passes through a double slit, a bright fringe is formed due to a path difference of
    A) 1/4 "wavelength symbol"
    B) 1/2 "wavelength symbol"
    C) 3/4 "wavelength symbol"
    D) 7/8 "wavelength symbol"
    E) 1 "wavelength symbol"

    please help by starting me off.
    gracias :)
  2. jcsd
  3. Jun 1, 2008 #2


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    Staff Emeritus
    Science Advisor

    You need to make at least some effort. What have you studied in class on this topic?
  4. Jun 1, 2008 #3
    Start with the definitions(what do monochromatic and slit imply?) and equations to solve this problem. Also, the wavelength symbol is the greek symbol lambda.
  5. Jun 1, 2008 #4
    for maxima (bright fringe)
    lambda / d = x/L
    where lambda is wavelength, d is distance between slits, x is distance of bright fringe, L is distance of screen from slits.

    lamda = xd/L
    answer is E) 1 lambda
  6. Jun 1, 2008 #5
    for bright fringe, path diff is n*lambda
    for dark band, it is (2n - 1)*lambda/2
  7. Jun 1, 2008 #6
    this is a question that was in my REA SAT II physics book. we never studied this in my physics class a year ago. and there's no mention of it in my REA book. or other study books i have.
  8. Jun 1, 2008 #7
    that's what the book says the answer is.
    but, i'm still really confused.
    so the fact it's a double slit doesn't matter??
    and that we don't know x and L?
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