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Questions for those who know electromagnetism better than I do

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emece67:
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Slartibartfast:

--- Quote from: HuronKing on December 16, 2021, 04:31:05 am ---
--- Quote from: Slartibartfast on August 27, 2021, 06:41:05 pm ---
--- Quote from: imo on August 25, 2021, 09:28:56 am ---My first lecture on "EM Field Theory" started with an intro given by the professor - "..do you really think the electrons transfer the energy from the power station to your household?? Have you ever seen an electron?? Electron is small and lightweight, almost nothing.. Moreover, the electrons travel a few centimeters in a second in a copper wire.. You would never have lit a lamp on your desk if it had worked that way.."

--- End quote ---

An exceedingly silly rant, if it really happened. Of course the marching electrons (a.k.a. current) need the electric field (a.k.a.) voltage, to, as the multiplicative product, deliver the power. Makes you wonder, if the uphill bicyling professor cannot find out where his efforts go, surely not into the movement (a.k.a. velocity)? Completely analogous, the velocity needs the backwards pulling force, to, as the product, become the power sink that makes him pant.

I'd consider this a way to confuse students, a pedagogical desaster.

--- End quote ---

What about reactive power and power factor? Complex power is, well, more complex than simply P = IV.

--- End quote ---

Sorry, there is nothing complex about P(t) = I(t) * V(t), and yet it is true.

Usage of complex numbers is a simplification for the case of single frequency (sine) AC. If you want to use it in the more general case, you have to deal with the complexities of using a simplification in a case where it is not simple anymore.

RJSV:
  eejeffrey has it right: (see comments back a bit), the thickness, of a pipe doesn't matter, for perfect round the fields cancel, in the interior...
  (I was just too timid, but confirmed the wire diameter issue, / non-issue. thanks

KE5FX:

snarkysparky:
still waiting for someone to explain to me how a constant E and constant B field at a point in space can imply that any energy is flowing *through* that point.

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