Bright Fringes (Intro to Quantum Physics Qestion?)

  1. 1. The problem statement, all variables and given/known data
    The distance between two slits is 0.05mm and the distance to the screen is 2.5m. What is the spacing between the central bright fringe and the first-order fringe? Use yellow light with a wavelength of 580nm


    2. Relevant equations
    xm=mλL/d


    3. The attempt at a solution
    L=0.5mm d=2.5m λ=580nm
    xm=(1)(580x10-9)/(.5x10-3) = .00116m
    (all the numbers were converted to meters)

    Whenever I plug these problems in, I get a strange answer that isn't anywhere near the multiple choice answers. What am I doing wrong?

    Multiple choice answer possibilities:
    a) 0.01m
    b) 0.029m
    c) 0.29
    d) 0.1m
    e) 0.6m
    I don't want the answer, I want to know what I did wrong here. If you get the right answer, please help!
    Cheers,
    ~a distressed AP student
     
  2. jcsd
  3. dx

    dx 2,000
    Homework Helper
    Gold Member

    Hi megoka,

    You mixed up L and d. L is the distance to the screen 2.5 m, and d is the space between the slits 0.05 mm.
     
  4. d=0.5mm L=2.5m λ=580nm
    xm=mλL/d

    x=(1)(580x10^-9)(2.5)/(0.5x10^-3)=.0029
    Okay!

    Thanks! I got my answer.
     
    Last edited: Apr 21, 2009
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