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Homework Help: Phase Difference

  1. Oct 19, 2011 #1
    1. The problem statement, all variables and given/known data
    Sources A and B emit long-range radio waves of wavelength 550 m, with the phase of the emission from A ahead of that from source B by 90°. The distance rA from A to a detector is greater than the corresponding distance rB from B by 140 m. What is the magnitude of the phase difference at the detector?


    2. Relevant equations



    3. The attempt at a solution


    Initially, source A leads source B by 90°, which is equivalent to \frac{1}{4} wavelength.
    However, source A also lags behind source B since rA is longer than rB by 140 m, which is \frac{140}{550}=0.2545 wavelength. So the net phase difference between A and B at the
    detector is -0.732 Rad.

    This is wrong though, can someone help me =D
     
    Last edited: Oct 19, 2011
  2. jcsd
  3. Oct 19, 2011 #2

    vela

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    How'd you come up with -0.732 rad? It looks like you completely ignored one of the terms.
     
  4. Oct 19, 2011 #3
    To be honest I'm not sure.
    I have tried everything I can think off but all my answers are wrong.
     
  5. Oct 19, 2011 #4
    Thank you for your time but I asked a friend and he showed me. It was just a stupid mistake that I missed thank yiu
     
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