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Electrons and Consequences of Conservation Laws

  1. Feb 15, 2015 #1
    Hi Guys,

    I was wondering; if electronic charge is conserved by Kirchoff's Current Law, then does this mean that the total number of electrons traversing any given circuit at any time is constant?
  2. jcsd
  3. Feb 15, 2015 #2


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    How do you define "traversing any given circuit"?
    The total number of charges in the whole circuit is constant, sure.
    In typical materials, most of the electrons are bound and never contribute to current flows.
  4. Feb 15, 2015 #3
    Why do you think current must be constituted only of electrons flow? That's correct for metals, but not correct always.
  5. Feb 15, 2015 #4

    jim hardy

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    A question well phrased is half answered.

    mfb highlighted the ambiguity in your question

    do you mean "traversing" a series circuit ? At what sort of frequency ?
    by "constant" do you mean with respect to time, or the same in all parts of the circuit?

    The answer to your question would be
    "In a flashlight, yes.
    In a transmission line, no."

    and one needs to be constantly aware of difference between electron drift and current....
  6. Feb 15, 2015 #5


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    As usual, I feel I need to chip in here and discourage approaching 'electricity' in terms of electrons when it's not absolutely necessary. They seem to cause more confusion than they are worth - in this thread, as in many others.
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