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Veritasium "How Electricity Actually Works"

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EEVblog:
Dereks's video at 21:10 Re. Rick Hartley about fields is 100% correct for high speed PCB design. But that does NOT apply at DC, not at all, not even one tiny bit.

EEVblog:
I posted this comment on Derek's video, slighly expanded:

Riddle me this, a new thought experiment: Let's go extreme and say you have a 100mm diameter copper conductor at pure steady state DC delivering a small amount of power to a pure resitive load, say 1W, but go as low as you want. No transients, no skin effect, no nothing, just pure steady state DC into a resistive load.
Is there NO energy WITHIN this comicly large wire? None? It's all on the OUTSIDE of the wire in the fields at DC? Really? REALLY?

The classicial field theory math might work at DC, but I just can't get over the feeling that it doesn't pass the sniff test at DC. I don't get The Vibe I get with AC and transients. Quantum Electrodynamics and probability theory in the electron fields within the wire better passes the sniff test at DC.

Can someone please convince me that there is no energy flow within this 100mm diameter wire at all, and that all the energy flows outside the wire at DC.

bsfeechannel:

--- Quote from: EEVblog on May 02, 2022, 05:43:26 am ---Hontas Farmer is back still saying the Derek is both right and wrong acording to QFT/QED



--- End quote ---

Double-posting, Dave?

https://www.eevblog.com/forum/chat/veritasium-(yt)-the-big-misconception-about-electricity/msg4150432/#msg4150432

Anyway, I commented there and won't repeat it here.


--- Quote from: EEVblog on May 02, 2022, 12:31:57 pm ---The classicial field theory math might work at DC, but I just can't get over the feeling that it doesn't pass the sniff test at DC. I don't get The Vibe I get with AC and transients. Quantum Electrodynamics and probability theory in the electron fields within the wire better passes the sniff test at DC.

--- End quote ---

Think for a bit. If you are convinced that energy doesn't flow in the wires for AC (or RF for that matter), why would it for DC?. Doesn't it take more energy to push electrons to and fro than to let them go indefinitely in the same direction?

EEVblog:

--- Quote from: bsfeechannel on May 02, 2022, 01:33:23 pm ---Double-posting, Dave?

https://www.eevblog.com/forum/chat/veritasium-(yt)-the-big-misconception-about-electricity/msg4150432/#msg4150432

--- End quote ---

Yes, because there are now two threads, and many people are not reading the other thread any more.

T3sl4co1l:

--- Quote from: EEVblog on May 02, 2022, 12:31:57 pm ---I posted this comment on Derek's video, slighly expanded:

Riddle me this, a new thought experiment: Let's go extreme and say you have a 100mm diameter copper conductor at pure steady state DC delivering a small amount of power to a pure resitive load, say 1W, but go as low as you want. No transients, no skin effect, no nothing, just pure steady state DC into a resistive load.
Is there NO energy WITHIN this comicly large wire? None? It's all on the OUTSIDE of the wire in the fields at DC? Really? REALLY?

The classicial field theory math might work at DC, but I just can't get over the feeling that it doesn't pass the sniff test at DC. I don't get The Vibe I get with AC and transients. Quantum Electrodynamics and probability theory in the electron fields within the wire better passes the sniff test at DC.

Can someone please convince me that there is no energy flow within this 100mm diameter wire at all, and that all the energy flows outside the wire at DC.

--- End quote ---

Easy:

1. The given problem is a dynamics problem.  Therefore we're only concerned with AC behavior.

2. He does discuss field within a conductor (though not how it gets there -- skin effect bridges the "AC" and "DC" regimes, as it turns out).  And we can solve for the energy density of that field.  It is terribly small in comparison, but nonzero.

The fact that most of the system's energy is stored in the magnetic field around the wires, hints further that "energy flows outside the wires", but this is an interpretation, and one can take either point; they're equivalent, once everything's quiescent, i.e. you can solve from one given the other (and material properties, boundary conditions, all that).

That is, the E-field inside the wire, given its resistance, tells the current density, and the wire diameter give the total current, and the wire placement is given, so the magnetic field can be solved.

Tim

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