Veritasium "How Electricity Actually Works"

[electrodacus]

Of course, in vacuum, electron beams flow quite nicely.
In air, they flow less nicely in the form of arcs, sparks, and lightning.

The amount of energy flow through air can be ignored in Derek's experiment due to super low potential 20V and large gap 1m between the two conductors.

[SandyCox]

How does sunlight get to the earth? Do you see wires connected between the sun and the earth?

Sun provides energy to earth through photons with most of the energy delivered in infrared but also what we call visible light and a bit of UV
With the photoelectric effect so photons will transfer their energy to electrons.

Are you aware of the fact that light is an electromagnetic wave? Just like radio waves.

[vad]

Wire is used as a medium to transport energy. If wire has resistance then part of the energy will be wasted in the wire so less of the energy will be available to your load.

This is interesting hypothesis, but it has nothing to do with reality, unless:

1) Classical Electrodynamics is off by huge amount at non-relativistic macroscopic scale (scale of the last Veritasium experiment).

or

2) Law of conservation of energy is broken

Proving any of these experimentally would earn a Nobel Prize

[electrodacus]

Are you aware of the fact that light is an electromagnetic wave? Just like radio waves.

Yes visible light is part of the electromagnetic spectrum. Sun is not providing electrical energy directly we convert photons into electric current flow through different mechanisms.

Maybe thermal energy is easier to understand. You can transfer that through radiation (infrared photons) in all directions so not very effective is you want to transfer that to a particular object and then you have thermal conductors (it just happens to be that electrical conductors are also good thermal conductors) so if you want to transport thermal energy you will use a thermal conductor and energy will flow through that thermal conductor not around it.
 

[electrodacus]

Wire is used as a medium to transport energy. If wire has resistance then part of the energy will be wasted in the wire so less of the energy will be available to your load.

This is interesting hypothesis, but it has nothing to do with reality, unless:

1) Classical Electrodynamics is off by huge amount at non-relativistic macroscopic scale (scale of the last Veritasium experiment).

or

2) Law of conservation of energy is broken

Proving any of these experimentally would earn a Nobel Prize

Where do you see broken law of conservation of energy in any of my statements ?
And how what I said has nothing to do with reality when that is exactly what you see in reality including Derek's experiment.

[ejeffrey]

Of course, in vacuum, electron beams flow quite nicely.
In air, they flow less nicely in the form of arcs, sparks, and lightning.

The amount of energy flow through air can be ignored in Derek's experiment due to super low potential 20V and large gap 1m between the two conductors.

Can you *calculate* how much?  Because I can using classical electrodynamics, and it agrees with what Derek showed and also his original thought experiment with wires going to the moon.  Both versions show that an appreciable fraction of the steady-state power can be transferred before the ends of the wire are causally relevant.  The exact amount depends on the load and the wire spacing.  The only part I can't "calculate" is the cutoff where I stop saying that the energy is transferred through space and it starts being transferred via the wire.  That is because no such cutoff actually exists, and the practice of doing so is a convenient low frequency approximation of electrodynamics that can explains some but not all circuit phenomena.

[electrodacus]

Can you *calculate* how much?  Because I can using classical electrodynamics, and it agrees with what Derek showed and also his original thought experiment with wires going to the moon.  Both versions show that an appreciable fraction of the steady-state power can be transferred before the ends of the wire are causally relevant.  The exact amount depends on the load and the wire spacing.  The only part I can't "calculate" is the cutoff where I stop saying that the energy is transferred through space and it starts being transferred via the wire.  That is because no such cutoff actually exists, and the practice of doing so is a convenient low frequency approximation of electrodynamics that can explains some but not all circuit phenomena.

If you did not already check this post I made yestarday https://www.eevblog.com/forum/chat/veritasium-how-electricity-actually-works/msg4168171/#msg4168171

[vad]

Where do you see broken law of conservation of energy in any of my statements ?
And how what I said has nothing to do with reality when that is exactly what you see in reality including Derek's experiment.

You claim that in addition to energy that is flown away from battery by electromagnetic field (that an average STEM undergrad can compute using Poynting vector and calculus at least for DC case), there is additional flow of EM energy inside wire along its axis. This additional energy can’t come from the battery, because all battery energy either flows inside the wire perpendicular to its axis causing Joule heating, or flows outside wire towards load, as can be show by STEM uni student.

So this additional EM energy that you claim flows inside wire along its axis comes from nowhere, and further discussion should move to “over unity” section of this forum.

[electrodacus]

Where do you see broken law of conservation of energy in any of my statements ?
And how what I said has nothing to do with reality when that is exactly what you see in reality including Derek's experiment.

You claim that in addition to energy that is flown away from battery by electromagnetic field (that an average STEM undergrad can compute using Poynting vector and calculus at least for DC case), there is additional flow of EM energy inside wire along its axis. This additional energy can’t come from the battery, because all battery energy either flows inside the wire perpendicular to its axis causing Joule heating, or flows outside wire towards load, as can be show by STEM uni student.

So this additional EM energy that you claim flows inside wire along its axis comes from nowhere, and further discussion should move to “over unity” section of this forum.

Have you seen the post where I made the Spice simulation showing energy output from the source and the energy at the lamp/resistor ?
https://www.eevblog.com/forum/chat/veritasium-how-electricity-actually-works/msg4168171/#msg4168171

You have a wrong understanding of what energy is and how it is transferred from source(battery) to load (lamp/resistor).
The graphs I posted there for two cases show exactly how energy travels.
Also an incandescent lamp is nothing more than a wire with higher resistance so is the 1KOhm resistor Derek used in his experiment.

[vad]

Have you seen the post where I made the Spice simulation showing energy output from the source and the energy at the lamp/resistor ?
https://www.eevblog.com/forum/chat/veritasium-how-electricity-actually-works/msg4168171/#msg4168171

You have a wrong understanding of what energy is and how it is transferred from source(battery) to load (lamp/resistor).
The graphs I posted there for two cases show exactly how energy travels.
Also an incandescent lamp is nothing more than a wire with higher resistance so is the 1KOhm resistor Derek used in his experiment.

You are using wrong tools. Spice by no means can be used to simulate electromagnetic field in matter and space.

Also, at DC, you did not have to go that far by drawing what looks like a transmission line. 3 resistors (one for load and two for each wire), a battery and a ground symbol are sufficient for DC analysis in Spice.

[IanB]

You have a wrong understanding of what energy is and how it is transferred from source(battery) to load (lamp/resistor).

If on the one side we have electrodacus, who is right, and on the other side we have the rest of the world, who are wrong, then really all rational people would wish to be with the rest of the world and remain wrong. Apparently, in this scenario, being wrong is the right place to be.

[electrodacus]

You are using wrong tools. Spice by no means can be used to simulate electromagnetic field in matter and space.

Also, at DC, you did not have to go that far by drawing what looks like a transmission line. 3 resistors (one for load and two for each wire), a battery and a ground symbol are sufficient for DC analysis in Spice.

That transient when you are closing the switch (with is what Derek concentrated on) is not DC.
All that was needed and if you understood the graphs is exactly what Derek got as a result just wrongly explained the reason for that result.

[electrodacus]

If on the one side we have electrodacus, who is right, and on the other side we have the rest of the world, who are wrong, then really all rational people would wish to be with the rest of the world and remain wrong. Apparently, in this scenario, being wrong is the right place to be.

It is very clearly most engineers understand as well as I do how things work so are most Physicists.
There is no evidence against what I'm saying and no evidence for the claim that "energy doesn't flow in wires"
It is not the first time when Derek shows his inability to understand energy and energy conservation.

Way waste resources to do the transmission line experiment when we know (some of us) how to simulate that.
I got the exact same result from stimulating a transmission line as it is much easier to take measurements there including integrating power to get energy at different points.
So is not as you think me against the world it is me doing my best to educate you.

[ejeffrey]

I think that's missing an important thing. No doubt we are all mostly agreed that there is some fields stuff going on before the wires are connected, but what it's really about is after that, when there is a solid wired connection. Does the energy flow in the wire, on the wire (skin) or is the wire merely a guide and the energy actually flows still in the field? As I see it, and it's sometimes tricky to remember what the argument is about, it's that last option which is the crux of the video and this discussion.

For me the question is entirely about DC and energy inside vs outside the wire. Nothing to do with switches, transmission lines, capacitors, inductors, transformer theory, antenna theory etc etc.

For steady currents you can calculate energy density (ignoring prefactors and constants of nature) as qV + I*Phi [Phi == magnetic flux]. or E^2+B^2 and you will get the same answer.  The former describes the electric energy in terms of charges, the latter in terms of fields.  You can't really get away from describing the magnetic component in terms of some field in free space because there is no scalar magnetic potential, so I have picked a form where the current plays a role, but I don't need to refer to equivalent circuit elements like L.

Taking only the electric component qV, that is zero on the interior of a conductor because the net charge density is zero.  There is a small electric field inside the wire to overcome the wire resistance but the net charge density is zero.  The only place with a net charge density is the surface of the wire, and in the charge model that is where all the electrostatic energy is stored.  Even though the current is uniformly distributed across the wire cross section there is no (electrostatic) energy density there.

The magnetic component is harder to nail down.  For the field centric approach it's no problem: B is unambiguously defined everywhere, so we can just integrate up B^2.  But the flux * Phi representation is sort of inherently non-local: its is the current around a loop times the magnetic flux through the loop, so a product of quantities measured at two different locations.

So at DC, you can consistently define the electric component of the energy density to the wire *surface* as an alternative to the fields.  When you include the magnetic component or deal with AC or transient behavior you pretty much have to fall back to a field based approach to energy density.  There is no reasonable way to quantitatively define the energy to be stored in the volume of the wires. 

[vad]

That transient when you are closing the switch (with is what Derek concentrated on) is not DC.
All that was needed and if you understood the graphs is exactly what Derek got as a result just wrongly explained the reason for that result.

I thought you were referring to DC when you wrote this: “ The difference is that with DC the energy flow is uniform inside the wire meaning the entire section of the wire is used while with AC the higher the frequency and line capacitance the more charges will flow closer to the surface forming the capacitor.”

No matter DC, AC or transient analysis - you are using wrong tools.

[hamster_nz]

I'm starting to come around to the idea that the electrons carry the energy, and it's not in the fields around.

All it would take to convince me would be if somebody could design a circuit that could extract 1% of the energy travelling in the wires in the diagram attached.

If you could build it inside the inner 'box' of wires that would be perfect, as I suspect an electric field exists between the inner and outer wires... You could even use a GND reference in the box if you want (but note that none of these wires are attached to GND)

[Naej]

I think that's missing an important thing. No doubt we are all mostly agreed that there is some fields stuff going on before the wires are connected, but what it's really about is after that, when there is a solid wired connection. Does the energy flow in the wire, on the wire (skin) or is the wire merely a guide and the energy actually flows still in the field? As I see it, and it's sometimes tricky to remember what the argument is about, it's that last option which is the crux of the video and this discussion.

For me the question is entirely about DC and energy inside vs outside the wire. Nothing to do with switches, transmission lines, capacitors, inductors, transformer theory, antenna theory etc etc.

For steady currents you can calculate energy density (ignoring prefactors and constants of nature) as qV + I*Phi [Phi == magnetic flux]. or E^2+B^2 and you will get the same answer.  The former describes the electric energy in terms of charges, the latter in terms of fields.  You can't really get away from describing the magnetic component in terms of some field in free space because there is no scalar magnetic potential, so I have picked a form where the current plays a role, but I don't need to refer to equivalent circuit elements like L.
[...]
The magnetic component is harder to nail down.  For the field centric approach it's no problem: B is unambiguously defined everywhere, so we can just integrate up B^2.  But the flux * Phi representation is sort of inherently non-local: its is the current around a loop times the magnetic flux through the loop, so a product of quantities measured at two different locations.

So at DC, you can consistently define the electric component of the energy density to the wire *surface* as an alternative to the fields.  When you include the magnetic component or deal with AC or transient behavior you pretty much have to fall back to a field based approach to energy density.  There is no reasonable way to quantitatively define the energy to be stored in the volume of the wires.

Yes there is, you replace whatever phi is by A the vector potential, and you get the potential energy.

[TimFox]

Actually there is a scalar magnetic potential, but it is not relevant to general field calculations.
It is used in electromagnet design, including air gaps, and is analogous to scalar electric potential in a circuit, replacing resistance (electrical) by reluctance (magnetic).

[Naej]

I'm starting to come around to the idea that the electrons carry the energy, and it's not in the fields around.

All it would take to convince me would be if somebody could design a circuit that could extract 1% of the energy travelling in the wires in the diagram attached.

If you could build it inside the inner 'box' of wires that would be perfect, as I suspect an electric field exists between the inner and outer wires... You could even use a GND reference in the box if you want (but note that none of these wires are attached to GND)

First show your solution for a circuit which extract 1% of the energy travelling in the vacuum in the diagram.

[vad]

So at DC, you can consistently define the electric component of the energy density to the wire *surface* as an alternative to the fields.  When you include the magnetic component or deal with AC or transient behavior you pretty much have to fall back to a field based approach to energy density.  There is no reasonable way to quantitatively define the energy to be stored in the volume of the wires.

There are devices that can store energy within conductive media. They call them lasers and masers, including RF masers.

However copper tubes in Veritasium experiment hardly qualify for a maser

[vad]

First show your solution for a circuit which extract 1% of the energy travelling in the vacuum in the diagram.

Create vacuum in the box and heat the outer wire (cathode) high enough so sufficient number of electrons will flow towards the inner wire (anode) to tap the 1% of energy.

They call this a diode vacuum tube, don’t they?

Now is your turn.

[hamster_nz]

First show your solution for a circuit which extract 1% of the energy travelling in the vacuum in the diagram.

Create vacuum in the box and heat the outer wire (cathode) high enough so sufficient number of electrons will flow towards the inner wire (anode) to tap the 1% of energy.

They call this a diode vacuum tube, don’t they?

Now is your turn.

That was along the lines of what I was thinking...

[PlainName]

you will see that the conductor heats uniformly on the entire conductor cross section

Easy for you to say. How about you demonstrate that?

People tested that well before I was born it just seems that internet instead of being this great learning tool it becomes a space for misinformation.
What about you just measure the electrical resistance of a copper pipe with thin walls and the electrical resistance of a copper bar with same diameter then let me know if there is a difference.
If there is a difference in resistance that means electrons from your multimeter traveled through the middle of the copper bar not just close to the surface.
You will see that resistance will be proportional with the copper section area so electron wave will travel uniformly through the material.

Woah! No-one's talking resistance here (except you, as a diversion). You said "you will see that the conductor heats uniformly on the entire conductor cross section" - that is heat, thermal. I am wondering just how you can measure the internal temperature of a conductor, and you Internet isn't any help there.

So, just how do you see that? If you make a hole and place a probe you're affecting the conductor integrity, and even with a thermal imager you're only going to see the outside.

Or was this just another 'fact' or 'law' you made up on the spot?

[electrodacus]

That transient when you are closing the switch (with is what Derek concentrated on) is not DC.
All that was needed and if you understood the graphs is exactly what Derek got as a result just wrongly explained the reason for that result.

I thought you were referring to DC when you wrote this: “ The difference is that with DC the energy flow is uniform inside the wire meaning the entire section of the wire is used while with AC the higher the frequency and line capacitance the more charges will flow closer to the surface forming the capacitor.”

No matter DC, AC or transient analysis - you are using wrong tools.

That is exactly what I said in reply to Dave.
I do not think I use the wrong tools as I do get the correct result and I want you to show me an alternative way to do it.

[electrodacus]

Create vacuum in the box and heat the outer wire (cathode) high enough so sufficient number of electrons will flow towards the inner wire (anode) to tap the 1% of energy.

They call this a diode vacuum tube, don’t they?

Now is your turn.

So you understand that energy transfer is done by the wave of electrons.  How many electrons flow from the wire/copper pipe in Derek's experiment ?
Should be very substantial and directional if you want to account for the energy transferred in the first 65ns. What about the rest ?