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I Surface Charge - Poynting Vector - DC circuit power flow

  1. Feb 1, 2017 #1
    I found it very interesting to see that surface charge and the Poynting vector are being used to describe how a simple DC circuit actually works. Chabay and Sherwood have made an outstanding contribution to physics and engineering in their texts and papers. Of course others jump on the bandwagon and rightly so with a plethora of papers in the last 15 years. We were not taught those truths back in 1970, a shame. Regarding the use of the Poynting vector to show power flow is not mainly in the wires most of the authors of recent papers neglect to mention that John Kraus in his "Electromagnetics" did indeed illustrate this. I know it is in his 2nd edition, 1973,
    pages 416-419. Unfortunately I didn't have his text but took E&M using Reitz and Milford and if it is in there its buried somewhere.
  2. jcsd
  3. Feb 1, 2017 #2
    I too was rather blown away that such basic understanding has only recently been truly resolved. Even Feynman already commented on this deficiency in one of his lectures. And even though my Master's in EE was rather theoretical in comparison to others, I certainly was not aware of it. Just like everyone else I assumed the energy was being transported inside the wire, very much like a water hose would work. And especially when one considers non-steady state circuits, where potential difference travel down the wire and get reflected etc, it even more so looks like that that part is carrying the energy.

    That said, from an engineering perspective it makes no difference of course. And the way I understand it, the energy gets transported just outside the wire, so it's essentially a difference of a few micrometer.
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