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Homework Help: What is the condition for the radiation term in the expression for the field B to

  1. Jan 11, 2012 #1
    1. The problem statement, all variables and given/known data

    What is the condition for the radiation term in the expression for the field B to predominate? Express you answer as a relationship between distance r and wavelength [itex]\lambda[/itex].

    B(r)=[itex]\frac{\mu_{0}I_{0}\delta l}{4\pi}[/itex]sinθ ([itex]\frac{-i\omega}{rc}[/itex]+[itex]\frac{1}{r^{2}}[/itex])exp[i(kr-[itex]\omega[/itex]t)][itex]\phi[/itex]-hat

    3. The attempt at a solution

    r>>[itex]\lambda[/itex]?
    But how was this result obtained? If r>>c/omega, r>>c/(2[itex]\pi[/itex]f), r>>[itex]\lambda[/itex]/(2[itex]\pi[/itex]), then how was the 2[itex]\pi[/itex] got rid of?

    If r>>c/[itex]\omega[/itex], why is this the case?

    Please help.
     
  2. jcsd
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