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"Veritasium" (YT) - "The Big Misconception About Electricity" ?

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bdunham7:

--- Quote from: bsfeechannel on January 03, 2022, 02:10:28 am ---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.

--- End quote ---

Yes, in QFT the fields are explained as exchanging virtual particles.  But I think you missed the point of Farmer's video.  As she pointed out, those exchanges are much, much more likely to occur along the wire rather than across the space.  If you actually used QFT and math to map all that out, you would indeed get fields that would match up with classic EM and the results would not 'disprove' Poynting or anything else in non-QFT physics.  But, if you actually DID all that--and I'm sure you aren't--the resultant fields, Poynting vectors and S-fields would not look like much the dramatized versions we have been seeing here with big arrows going through space from a battery to a load (and, b/t/w, omitting the equally big arrow going the other way from the battery).

Now as far as Derek's video, you continually misstate what others have said in order to prove them 'wrong'.  I didn't agree with Dave when he called you a troll, but I'm starting to wonder.  If you were to open the ends up on the long pairs of wires, you know full well that no current would flow through the load in the fully settled DC steady state and no power would be exchanged over that space via virtual particles or Poynting vectors.  You know that full well not because you will examine it with math, Poynting, QFT or advanced physics concepts, but rather because you simply apply Ohms law just like the rest of us blockheads.


--- Quote ---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.

--- End quote ---

IIRC, Dave and almost everyone else here has not somehow stated that Poynting's Theorem is incorrect.  You keep bringing that up and it just isn't true.  However...


--- Quote ---The Poynting vector is weird, but it is what is really going on there. Welcome to reality.

--- End quote ---

...I think you may be misinterpreting the meaning of the Poynting vector as opposed to the integration of the S-field over a closed surface.  Maybe.  I really don't know.  I'd have to think about that.  I'm not a Poynter.


--- Quote ---But, but, but, Derek did that in his video! Why should I redo what is already perfect?

--- End quote ---

Because his answer was the trivial 1m/c 'gimme' that we all understand, despite you attempting to repeatedly claim we don't whenever we omit the obvious.

bdunham7:

--- Quote from: Sredni on January 02, 2022, 02:12:20 pm ---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?

--- End quote ---

I downloaded that and was unable to get it to run (yes I read the instructions) and apparently you haven't either since you just posted the sample shot.  I'm not sure that it is complete or accurate, but maybe it doesn't matter.  What happens if you disconnect the first resistor right at the two ends?

bsfeechannel:

--- Quote from: bdunham7 on January 03, 2022, 05:27:04 am ---But I think you missed the point of Farmer's video.  As she pointed out, those exchanges are much, much more likely to occur along the wire rather than across the space.
--- End quote ---

What she said is that an electron has a much higher probability of interacting with another electron a billionth of a meter apart than with one 1 m away. Just that.

She says nothing about how this interaction will finally get to the lamp along a wire 300.000 km long with gazillions other electrons and protons. Not even how these electrons will rearrange themselves in the wire as a function of this interaction.

So her video was yet just another stunt to capitalize on the polemic generated by Derek's video.

Dave says that QFT contradicts Poynting, but it is in fact he who said that. Not QFT.


--- Quote ---IIRC, Dave and almost everyone else here has not somehow stated that Poynting's Theorem is incorrect.
--- End quote ---

Dave says it doesn't apply to DC. He's wrong. But the issue here is not technical, as Maxwell himself pondered on. It's difficult to accept that an analogy that you held dear turns out in the end to be superficial and misleading.

HuronKing:

--- Quote from: adx on January 02, 2022, 07:22:32 am ---
--- Quote from: Sredni on January 01, 2022, 09:09:39 am ---...
Or, if you want to fly a bit lower, Kraus

John D. Kraus
Electromagnetics 2e
section 10.20 Circuit Applications of the Poynting Vector
p. 416
on p. 418, after considering a circuit with a battery (DC) and a resistors he writes:

--- Quote ---"In Fig. 10-19aflow lines of the Poynting vector (power flow lines) are shown. It is evident that the power flow is through the empty space surrounding the circuit, the conductors of the circuit acting as guiding elements. From the circuit point of view we usually think of the power as flowing through the wires but this is an oversimplification and does not represent the actual situation."
--- End quote ---

--- End quote ---

This (italics mine). Is an example of an academic sermonising scientific hypothesis as fact. It may seem harmless, but results in generations(s) of disciples believing stuff.

--- End quote ---

I know this was already a page ago, but can we pause for a moment to appreciate that John D. Kraus, the inventor of the helical antenna and corner reflector array, is being called a sermonizing academic?
https://en.wikipedia.org/wiki/John_D._Kraus

I mean, you can call him wrong, and you'd be wrong to call him wrong, but Kraus was hardly an ivory tower academic who didn't build anything practical... he used his exquisite knowledge of Maxwell's equations and Poynting theory to create entirely new types of antennas and waveguides - and all without numerical EM-simulators that we take for granted.

SandyCox:
Let’s look at Haus and Melcher’s example 11.3.1 in more detail. We look at the example from the point of view of conservation of energy. We can calculate the power entering the washer from the voltage source. We can also calculate the power entering the rod from the voltage source.
We then use Poynting’s theorem to calculate the power that is dissipated in the rod and the power that is dissipated in the washer. It all ads up correctly. All the power that is delivered by the voltage source to the rod is dissipated in the rod.  All the power that is delivered by the voltage source to the washer is dissipated in the washer.
According to our misinterpretation of the Poynting vector, Fig 11.3.1 leads to the conclusion that power is being transferred from the washer to the rod through region (a). This simply isn’t happening.

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