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Split EM wave?

  1. Sep 12, 2012 #1
    Hi eveyone, I am new to this forum and I hope that I can gain lots from this forum.

    Recently, one question comes into my mind, that is about the possibility of splitting the electric component and magnetic component of EM wave. This two components seem to always stick together. However, if they can be separated, I believe, EM wave can do more things than it does now.

    Can someone help me to analyse the possibility of splitting the EM wave into its component? Your help is truly appreciated !

    Thank you !
     
  2. jcsd
  3. Sep 13, 2012 #2
    EM waves do not carry energy away from their source unless they have both an electric and magnetic component. This can be seen via Poynting's theorem:
    S=1/μ0(E×B)
    where S is a vector which is proportional to the energy flow in the EM fields E and B. So even if you can make an EM wave without a B component, it will not be very useful.

    In addition, in free space (as opposed to in a dielectric or in a region with boundary conditions imposed), any region in space where E varies over time must have nonzero B, due to Maxwell's equation:
    μ0ε0E/∂t=∇×B
    So under ordinary circumstances, B will be nonzero anytime there is a time-varying E.
     
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