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Magnetic field plane wave

  1. Apr 8, 2012 #1
    The magnetic field expression for an electric field of a plane wave in air in the time domain is H(t) = y3sin(ωt + 3x + 4z). Find the frequency of the wave.

    i am having trouble where to begin on this problem. i know how to solve if there is only 1 direction variable (i.e. just x or just z), but since there is an x and z inside the sin, i'm not sure what to do
     
  2. jcsd
  3. Apr 9, 2012 #2

    tiny-tim

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    hi magnifik! :smile:

    just change the variables … put k = 3x/5 + 4z/5 and see what happens :smile:

    (doing it in your head should be enough :wink:)
     
  4. Apr 9, 2012 #3
    is there a reason you chose the denominator as 5?
     
  5. Apr 9, 2012 #4

    tiny-tim

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    yes! :smile:

    and what is it? :wink:
     
  6. Apr 9, 2012 #5
    oh i get it. k = sqrt(3^2 + 4^2) = 5

    when i find E in phasor form from the given H, how do i know what direction it should be?
     
    Last edited: Apr 9, 2012
  7. Apr 10, 2012 #6

    tiny-tim

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    (just got up :zzz:)
    i'm confused :redface:

    doesn't it depend on the direction of polarisation? :confused:
     
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