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Electroboom: How Right IS Veritasium?! Don't Electrons Push Each Other??
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Naej:

--- Quote from: imo on July 02, 2022, 09:48:50 pm ---
--- Quote from: Naej on July 02, 2022, 09:19:55 pm ---
--- Quote from: imo on July 02, 2022, 06:48:48 pm ---
--- Quote from: electrodacus on July 02, 2022, 06:02:12 pm ---
--- Quote from: imo on July 02, 2022, 05:39:53 pm ---
And the kinetic energy of that amount of electrons would be something like 3*E-14 Joules..

--- End quote ---

That is wrong but please provide the details of how you came up with that number.
The electrical potential is 2V the current is 1A and over one second you get 2Ws that is the same with 2 Joules. So no matter how you make the calculation if you do things correctly you will get 2 Joules.

--- End quote ---

The kinetic energy of that N electrons per second (the amount N=6.25E18 you calculated) is

E = 1/2 * (N * me) * v^2, where me is the mass of an electron, and the v is the drift speed of the electrons in the copper, let say 1cm/s to be extremely optimistic..

E = 3E-16 Joules (each second) = 3E-16 Watts

--- End quote ---
No the speed of electrons is ~ 1600 km/s so you must multiply by 2e16 if you want to know the kinetic energy of electrons.

--- End quote ---

That 1570km/sec is the Fermi speed of electrons in the "electron gas" (random vectors inside the conductor) without any field imposed (no current). The average is zero. With a current the electron gas starts to drift with the speed "v".

--- End quote ---
You asked the kinetic energy of electrons. Their speed is ~ 1600 km/s.
The average of v^2 is not (the average of vector v)^2.

--- Quote from: imo on July 02, 2022, 09:48:50 pm ---Anyhow, to make the long story short - the energy in the circuits is not transferred via the conductors, but outside the conductors - along the conductors - via the Fields (the Electromagnetic Fields), where the strongest field is in a close vicinity of the conductor, and the intensity of the field decreases with distance off the conductor (but it spreads over entire Universe theoretically).
The fields propagate with the speed of light (in vacuum).

The Poynting vector shows the direction where the energy flows. The energy of the field is transferred to the "heat" when the field starts to enter the conductor with a higher "resistance" (it means the density of free electrons in such a "resistive" conductor is lower compared to a good conductor) and while the field enters the resistive conductor (and the Poynting vector bends towards the conductor) it comes to an energy transfer from the field to phonons (phonons are the "heat particles") also known as Joule's losses/heating (there is a change of the speed of the field propagation when it enters the conductor - speed slows down significantly - and transfers the energy into the phonons).

Therefore the lamp starts to lit, or a resistor starts to heat up, while the good conductors wired to them stay almost cold..

--- End quote ---
Yes. Also, the energy is transferred in the conductors and only light is outside of them. Electrons with high potential carry a lot of energy.
hamster_nz:

--- Quote from: eugene on July 02, 2022, 10:21:50 pm ---
--- Quote from: hamster_nz on July 02, 2022, 09:15:52 pm ---[...] here's why I think the energy flows in the two circuits are different, even though the voltages and currents are the same.

--- End quote ---

Should I conclude from that statement that you believe there's a way for electrical energy to flow other than via current?

--- End quote ---

I think that current is not energy. How much energy is there in 1A? 1 J or maybe 100 1 J ? I can make it either by changing the voltage but keeping the current the same!

And capacitors seem quite capable of transferring electrical energy between plates even though no charges are transferred between them.

Transformers seem quite capable of transferring large amounts of electrical energy between their primary and secondary windings even though no charges are transferred between them.

Inductive chargers also seem to work well enough for phones and electric toothbrushes.

DC-DC convertors can move electrical energy around, even though their inputs and outputs are electrically isolated.

So yes, of course I believe there's a way for electrical energy to flow other than via current! :-//

Current is just mobile charges moving in response to the local electric (and magnetic) field.
hamster_nz:

--- Quote from: Naej on July 03, 2022, 12:14:51 am ---Yes. Also, the energy is transferred in the conductors and only light is outside of them. Electrons with high potential carry a lot of energy.

--- End quote ---
An electron at high potential has as much energy as any other electron moving at the same speed speed.

In the schematic attached, when the ground connection is moved the electrons in the upper loop are not 'unburdened' of the energy they were carrying. They don't speed up. They don't slow down for them nothing changes.

Does the location of the ground connection make any difference to the heat in the resistor? It should, if the potential energy of each electron changes by 1000x.


electrodacus:

--- Quote from: hamster_nz on July 03, 2022, 12:34:04 am ---I think that current is not energy. How much energy is there in 1A? 1 J or maybe 100 1 J ? I can make it either by changing the voltage but keeping the current the same!

And capacitors seem quite capable of transferring electrical energy between plates even though no charges are transferred between them.

Transformers seem quite capable of transferring large amounts of electrical energy between their primary and secondary windings even though no charges are transferred between them.

Inductive chargers also seem to work well enough for phones and electric toothbrushes.

DC-DC convertors can move electrical energy around, even though their inputs and outputs are electrically isolated.

So yes, of course I believe there's a way for electrical energy to flow other than via current! :-//

Current is just mobile charges moving in response to the local electric (and magnetic) field.

--- End quote ---

Obviously current is not energy.

There are two ways to store electrical energy.

1) In a capacitor. A discharged capacitor is one that has the same number of free electrons on both plates. A charged capacitor will have extra electrons on one plate and deficit of electrons on the other plate.
2) In an inductor. Closed loop of wire that has a current flowing through it.  Normal conductors make for a terrible energy storage device as stored energy will be lost very fast but a superconductor is perfect as there is no resistance to electron flow so current flows forever (as far as we can measure).

Energy stored in a capacitor is 1/2 * Q * V and nothing more.
Q = I * t   Say I =1A and t = 1s that will be Q = 1C
You need about this much more free electrons on one plate compared to the other 6,250,000,000,000,000,000 in order to have 1 Coulomb of charge.
V = Q/C
The voltage depends on Capacitance that depends on the plates area and distance between the plates plus the type of material used between plates but it can be just vacuum or air.

The only way to use that stored energy is to create the conditions for the electrons to move from one plate to another so basically short circuit the two plates with some materials that allows electrons to travel trough like say a copper wire.
The smaller the resistance to current flow the faster those electrons can move to the other side making both plates neutral with equal number of electrons thus a discharged capacitor.

The 1/2 in the energy equation is because the voltage will drop as the capacitor is discharged.

So energy does not flow through a capacitor as that will mean electrons being able to jump through the gap between capacitor plates and if that was to be the case you will not call that a capacitor or at best a damaged capacitor meaning no longer works as a capacitor.

The energy either flows out of the capacitor if you are discharging it by connecting a wire between the two plates or energy flows in if you are charging the capacitor but energy will not flow through the capacitor (leakage current in real capacitors is small and we can ignore for this discussion).
electrodacus:

--- Quote from: hamster_nz on July 03, 2022, 12:56:00 am ---An electron at high potential has as much energy as any other electron moving at the same speed speed.

In the schematic attached, when the ground connection is moved the electrons in the upper loop are not 'unburdened' of the energy they were carrying. They don't speed up. They don't slow down for them nothing changes.

Does the location of the ground connection make any difference to the heat in the resistor? It should, if the potential energy of each electron changes by 1000x.

--- End quote ---

Again there is no difference between those two schematics.
You can connect that ground symbol anywhere you want and it will make no functional difference.
That 1000V battery is also completely useless and plays no role in any of the two schematics.
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