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"Veritasium" (YT) - "The Big Misconception About Electricity" ?
bsfeechannel:
--- Quote from: bdunham7 on January 03, 2022, 01:09:58 am ---
--- Quote from: bsfeechannel on January 03, 2022, 12:27:06 am ---So are the others who said he is wrong. All of them have talked out of their butts. Lots of views. All opinion. No facts.
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Like your post right there?
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Views? I have not published any videos about the subject. And haven't collected a single penny from it. How can I be a marketing genius?
--- Quote ---Did I miss the post where you used those to accurately predict the behavior the circuit in question before experiments were done? If I did could you link it for me or give me the reply#? I apologize in advance if you did post such an analysis. And I don't mean the trivial answer of 1m/c that despite allegations of engineers not understanding light speed due to dumbness, very few people here actually missed.
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But, but, but, Derek did that in his video! Why should I redo what is already perfect?
bsfeechannel:
--- Quote from: adx on January 03, 2022, 01:33:42 am ---Yet, like it or not, QFT has provided a 'worldview' which assists in 'debunking' (intentionally being loose with that wording) Poynting's vector as a source of truth for power flow at DC, a situation which is not far off being untestestable. It would require the experimental capabilities of Henry Cavendish's Earth density determination squared.
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Debunking? You got to be kidding me. QFT in fact confirms the Poynting vector at DC or at any frequency. The idea that nothing is happening at DC so the energy cannot flow through the fields is a misconception. At DC, AC, whatever, the electrons are exchanging virtual particles. That's why energy flows in the fields, even if the fields are not changing or moving.
Dave thinks that the Poynting vector does not work at DC because he is a circuit-headed engineer. The only way he can think of the energy traveling through space is when you have AC or RF. At DC no worky, because capacitors, transformers, and antennas, which are the only devices he knows that allow the transmission of energy through space, block DC.
I understand what Dave feels because a lot of engineers have trouble to reconcile their practical experience with the underlying concepts of the physical phenomena they are dealing with. In fact this is not new. Since scientists started to study electromagnetism they were faced with the non intuitive character of this phenomenon and expressed their puzzlement in their treatises.
The Poynting vector is weird, but it is what is really going on there. Welcome to reality.
Sredni:
--- Quote from: SandyCox on January 02, 2022, 05:52:39 pm ---
--- Quote ---Consider this other example:
source: https://www2.oberlin.edu/physics/dstyer/CircuitSurveyor/help.html
Is the fact that the first resistor in the above figure is getting all the field lines coming from the battery what you find of concern?
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Thank you for this example. It makes my point even clearer. According to the Poynting vector, energy is transferred from one resistor to the other. We know this isn’t what is happening.
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What I see here is that each resistor takes the energy that competes to it and let the rest go.
Much in the same way a partially absorbing glass will let most of the light through. Energy is still coming from the source, not the glass. (the main difference is that the wires makes it irrelevant what the positions of the glass pan--- the resistors are with respect to the source)
--- Quote ---Energy is transferred from the source to each resistor and not from one resistor to the other!
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And yet, if you consider the fact that in this system the magnetic field is uniform inside the loops (the circuit is a 2D slice of infinitely long cylindrical circuit to simplify the math), the direction of the Poynting vector is the same as that of the equipotentials of the electric field. And you cannot deny that the electric field is in the space between the resistors (there is none in the wires) and its configuration depends on the the surface charge on all resistors. The wires make it easier to 'conduct' the electric field at the resistors and do so with relaxation times, but once the surface charge has settled, the resultant field is in the space between resistors (and inside the resistors).
Enclose each resistor in a gauss surface and compute the net flux of S through that closed surface to find the power absorbed and you will see that each resistor is getting the power corresponding to V times I. Do the same with the battery and you will see that the battery is losing power corresponding to that absorbed by the three resistors, not the first one alone. Battery spits power out, resistors suck 'their' power in.
rfeecs:
You can't argue with math. The Poynting theorem derived from Maxwell's equations in 2 and half minutes flat:
adx:
--- Quote from: Sredni on January 03, 2022, 02:12:48 am ---Enclose each resistor in a gauss surface and compute the net flux of S through that closed surface to find the power absorbed and you will see that each resistor is getting the power corresponding to V times I. ...
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Do the same procedure on some space inside the loops but not where wires or resistors are. Then tell me how the result in any way supports the concept that "power doesn't flow in the wires"?
(Yes I'm aware of what will happen if you include some wire. That's not the question.)
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