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HELP Two point source interference pattern

  1. May 7, 2013 #1
    1. The problem statement, all variables and given/known data
    2 point sources 20cm apart produce 3 cm waves at a rate of 8 waves every 1.2 seconds

    2. Relevant equations
    how many nodal lines are present
    what is the angular deviation of the 3rd nodal line?
    what is the angle between the 3rd nodal line and the 5th nodal line?

    3. The attempt at a solution

    Answer for anyone who is wondering:
    Nodal lines:
    1 = (n-1/2) x wavelength
    1 = (n-1/2) x 3
    n = 7.17
    Nodal Lines on both sides of right bisector, 7.17 x 2 = 14 (rounded down to nearest whole number)
    Angular Deviation:
    sinx = (n-1/2) x wavelength/d
    x = sin-1(2.5 x (3/20))
    x = 22 degrees
    Angle between 3rd and 5th:
    Repeat steps above to find angle of 5th nodal line and subtract angle of 4rd from angle of 5th
    Last edited: May 7, 2013
  2. jcsd
  3. May 7, 2013 #2


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    Science Advisor
    Homework Helper
    Gold Member

    It is not good enough just to post the question. you must post your attempt at a solution; or if you can't even get started explain why not. Is it that you don't understand some of the terms or concepts? E.g. do you know what a nodal line consists of?
    To get you started, try http://www.physicsclassroom.com/Class/light/u12l1b.cfm
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