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Phase Difference - 3D

  1. Oct 11, 2007 #1
    1. The problem statement, all variables and given/known data

    A wave at the origin expands outwards passing the points (.01, .03, .02) and (-.01, .015, .025). This wave has a wave speed, V_w = 346 m/s and frequency = 13100 HZ.

    What is the phase difference between these two points?

    2. Relevant equations

    v = (wavelength)(frequency)

    Phase Difference = 2pi (delta x) / Wave length

    3. The attempt at a solution

    I attempted to use the following:

    [(distance between points using 3D formula)/(wave length)] * 2pi = phase difference.

    This was in correct. I am gonna guess that it's because "Phase Difference = 2pi (delta x) / Wave length" is for a wave in one dimension. My question is how does the phase difference change in 3 dimensions? I attempted to use the surface area of a sphere but it also failed. Something is quite wrong.
  2. jcsd
  3. Oct 11, 2007 #2


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    Homework Helper

    Use the distance from the origin... the delta you need is the difference of the second point from the origin - the distance of the first point from the origin.
  4. Oct 12, 2007 #3
    Wonderful thanks.
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