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EM Wave question

  1. May 2, 2005 #1
    Does EM wave have to actually strike a surface to induce current or can the EM fields induce current from a distance?
  2. jcsd
  3. May 2, 2005 #2


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    You speak of two different physical phenomena when discussing EM waves, and electric and magnetic fields (EM fields as you collectively call them), as if they are the same. They are obviously very closesly related, since an EM wave is nothing more than the propogation of E and M fields through space; but yet not the same. In the case of fields, yes, you induce current from a distance every day when using any electrical device. In the case of a battery for instance, current is being induced over a distance including the distance between the positive and negative terminals of the battery when connected to a circuit. In an EM wave's case however, I ask you to consider the analogy of an ocean wave knocking over a sandcastle on the beach. What you ask in your question, in effect is; can the wave knock over the sandcastle before even reaching it?
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