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Veritasium "How Electricity Actually Works"
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TimFox:
One reason I mentioned waveguides as a way of transferring power:
Another group at my university needed to transfer power to the top of a 1 MV accelerator, to operate the cathode and auxiliary electronics referenced to the cathode.
They used a dielectric waveguide:  like a metal one, but with a high dielectric constant ceramic as the envelope.  It was long enough to hold off the 1 MV DC potential difference between the terminal and ground.
A CW magnetron down at ground potential launched power up the guide to a receiving antenna, where a simple (high speed) rectifier provided DC power for the terminal.
HuronKing:

--- Quote from: SiliconWizard on May 23, 2022, 05:13:13 pm ---It's been two threads and things are still running in circles.

While I do not agree with everything electrodacus has written, I understand his question here: I don't think I've really seen a proper answer (except possibly in the early stages of the first thread), neither on here or in Veritasium's videos, about the role of wires and why we actually needed them (but we do for sure.)

--- End quote ---

Wires are wave guides.

Fields emanate from charges - charges live in conductors and the field disturbances carry the energy which influences nearby charges or charges in other conductors. I posted a video a few replies ago that illustrates this. And Kraus in Chapter 10 makes this explicit when he describes the Poynting Vector in circuit theory terms in a chapter about wave guides (including showing what happens when an infinite conducting sheet is placed between battery and load and how this changes the shape of the Poynting vector field).

And Feynman includes a lecture on this:
https://www.feynmanlectures.caltech.edu/II_24.html


--- Quote ---In the last chapter we studied what happened to the lumped elements of circuits when they were operated at very high frequencies, and we were led to see that a resonant circuit could be replaced by a cavity with the fields resonating inside. Another interesting technical problem is the connection of one object to another, so that electromagnetic energy can be transmitted between them. In low-frequency circuits the connection is made with wires, but this method doesn’t work very well at high frequencies because the circuits would radiate energy into all the space around them, and it is hard to control where the energy will go. The fields spread out around the wires; the currents and voltages are not “guided” very well by the wires. In this chapter we want to look into the ways that objects can be interconnected at high frequencies. At least, that’s one way of presenting our subject.
--- End quote ---

The 'energy always travels in wires' people cannot hope to design, let alone explain, how a high-frequency waveguide works and how to CONTROL where energy is going.

rfeecs:

--- Quote from: SiliconWizard on May 23, 2022, 05:13:13 pm ---It's been two threads and things are still running in circles.

While I do not agree with everything electrodacus has written, I understand his question here: I don't think I've really seen a proper answer (except possibly in the early stages of the first thread), neither on here or in Veritasium's videos, about the role of wires and why we actually needed them (but we do for sure.)

--- End quote ---

You need the wires to guide the energy from the source to the load.

For the case of the battery powering the light, there is very little potential drop along the good conductor wires, so they set up the potential across the load.

The power dissipated in the load is VI.  For DC, based on conservation of charge, the current has to be the same everywhere in the circuit.  So the wires are also needed to provide a circuit for current to flow.

This is why you need the wires for DC.  It says nothing about where the energy is "flowing".  Based on conservation of energy, it flows out of the volume of space surrounding the battery and into the volume of space surrounding the load.

The energy flow could be inside the wires or through the empty space.

For AC it's a slightly different story.
electrodacus:

--- Quote from: HuronKing on May 23, 2022, 05:34:38 pm ---The 'energy always travels in wires' people cannot hope to design, let alone explain, how a high-frequency waveguide works and how to CONTROL where energy is going.

--- End quote ---

A lot of people still live in the 1800's when electrons did not exist.
We are discussing a DC transmission line yet Derek prefered to just concentrate at the first 65ns of transient that he has no understanding of.
Even if we ignore (because you do not understand) the energy storage that is responsible for the transient part what happens at steady state after that transient as there is no longer any fluctuating electric or magnetic field they are just constant. Yet lamp/resistor is using energy.

Answer the earlier question about shielding against magnetic and electric fields either the battery or the load so that no energy can be transferred ?
I can simply made a cut / gap in the conductor 1mm will be more than sufficient for 20V and I can stop the energy flow between the battery and lamp.
My 1mm gap example should pe proof enough for any sane person that energy travels through wires but somehow with no proof you like to think there energy magically travels outside the wire.
HuronKing:

--- Quote from: electrodacus on May 23, 2022, 05:47:12 pm ---A lot of people still live in the 1800's when electrons did not exist.
We are discussing a DC transmission line yet Derek prefered to just concentrate at the first 65ns of transient that he has no understanding of.
--- End quote ---

You still don't get the point of the experiment? To demonstrate the radiation of energy during a transient getting there faster than it could traveling through the wire alone which means some energy was radiated from the switch to the lamp. Ben Watson's simulation demonstrates this explicitly. I'm pretty sure the people who designed HFSS know about electrons...  :-DD :-DD :-DD


--- Quote ---Even if we ignore (because you do not understand) the energy storage that is responsible for the transient part what happens at steady state after that transient as there is no longer any fluctuating electric or magnetic field they are just constant. Yet lamp/resistor is using energy.
--- End quote ---

The Poynting vector is still established. See Kraus Chapter 10.


--- Quote ---Answer the earlier question about shielding against magnetic and electric fields either the battery or the load so that no energy can be transferred ?
I can simply made a cut / gap in the conductor 1mm will be more than sufficient for 20V and I can stop the energy flow between the battery and lamp.
My 1mm gap example should pe proof enough for any sane person that energy travels through wires but somehow with no proof you like to think there energy magically travels outside the wire.

--- End quote ---

And you'd be utterly mystified if the frequency of the voltage source changed in any way and the lamp could still illuminate.

I have another way. Put an infinite conducting sheet between the source and the load. This is actually a far more effective shielding mechanism. E-fields can still cross your gap. E-fields cannot get through the infinite sheet. ExH is zero. No energy flow. Again, see Kraus Chapter 10.

I would never use an air gap if, hypothetically, I wanted to guarantee no energy ever crosses from one circuit to another. How do you think coaxial cables or rectangular waveguides work?!?!  :o

The only thing special about DC is that the waveguide has to guide the wave the whole way at steady-state.
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