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Veritasium "How Electricity Actually Works"
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T3sl4co1l:
And so we come back to a central conceit of the (OP) problem: does energy "flow" matter?  Does it mean anything at all?

Not really.

You can store energy, and release energy, at will.  Nothing wrong with that.  You can say it goes through cables, pipes, whatever.  Also nothing wrong with that.

But it's not particularly important where and how it goes.

The likes of Feynman would be perfectly comfortable with such a view.  Feynman was a huge advocate of Lagrangian mechanics, where the position and path don't matter on an instantaneous basis, instead you solve for them using an overall energy argument.  (Which leads perfectly into QM where, not only is the path unimportant, but indeed the probability of every possible path, including classically-intuitively-absurd paths, has some effect and the total must be taken to find the correct result.)  In classical mechanics of course, we don't have to deal with a superposition of possible paths, but only the one unique path that gives "least action" (minimizes energy).  Then the path, the complete history for all time, of the particle or system or whatever, simply drops out of the equations and we can take its value at any particular point in space or time to find position, velocity, altitude, energy, whatever.

Applied to circuitry, I don't give a rat's ass what energy is flowing in my traces or cables or whatever, just that they handle enough voltage and current to do the job.  That capacity requirement will ultimately be some function of the energy flowing, sure, but that's not what's important, and there are easier ways to calculate it than from the energy or power.

And so, it is even less important whether that energy is "carried in" or "around" the wires.  Dude, it just gets there when it does!

(Even for antenna purposes, I don't know that it's very useful or meaningful, as anything near the active elements is necessarily near-field, and what's going on there, need not be representative of the radiated field.  You don't optimize on near fields, you optimize on radiated fields, you want to know gain and radiation pattern -- who cares what's going on near.)

I think most people here already know this, which is why the bulk of this thread has been occupied with a... different, related curiosity.

Tim
hamster_nz:

--- Quote from: Naej on May 09, 2022, 09:21:38 pm ---which explains clearly that it is a theory dictating where energy flows, not experiments.
Much like bsfeechannel, they don't point to experiments, because they cannot.

--- End quote ---
LoL.  Here's two experiments that show where energy flows.

Experiment 1:
Attached a transformer to 220V AC, and get (say) 9V AC @ 0.5A out the other side.  The wires never touch (due to insulation). How does that energy pass through the transformer?

The answer for some here seem to be : It can't. Because the energy flows in the wires. Those Watts coming out the transformer are not from the energy coming in.

Experiment 2:
Store energy into the middle of three capacitors in series. Energy is transferred even though no charges can pass around the entire loop. How is that possible?

The answer for some here seem to be : It isn't possible, because the energy flows in the wires. The energy in that middle capacitor isn't stored electrical energy, it's something else.

Question still not answered:
Why do electrons in a wire drift proportionally to the current (the flow of charge), and not the energy being transferred?

For some the answer is : I'm not sure that they even drift

For others the answer for some here seem to be : Electrons carry not only charge they also carry the energy. They all have little backpacks they carry their electrical energy around it, and when a battery is connect or disconnect a battery they all quickly fill or empty their backpacks as required, sometimes over great distances, exactly at the time the connection is made or broken.


Naej:

--- Quote from: hamster_nz on May 09, 2022, 11:02:33 pm ---
--- Quote from: Naej on May 09, 2022, 09:21:38 pm ---which explains clearly that it is a theory dictating where energy flows, not experiments.
Much like bsfeechannel, they don't point to experiments, because they cannot.

--- End quote ---
LoL.  Here's two experiments that show where energy flows.

Experiment 1:
Attached a transformer to 220V AC, and get (say) 9V AC @ 0.5A out the other side.  The wires never touch (due to insulation). How does that energy pass through the transformer?

The answer for some here seem to be : It can't. Because the energy flows in the wires. Those Watts coming out the transformer are not from the energy coming in.

--- End quote ---
Perhaps it's what they say.
What I say is that you get 4.5W consumed in the input, 4.5W produced in the output wires.
Potential is converted into momentum in the primary, this increases the momentum in the secondary which is then converted into potential (9V).

--- Quote from: hamster_nz on May 09, 2022, 11:02:33 pm ---Experiment 2:
Store energy into the middle of three capacitors in series. Energy is transferred even though no charges can pass around the entire loop. How is that possible?

The answer for some here seem to be : It isn't possible, because the energy flows in the wires. The energy in that middle capacitor isn't stored electrical energy, it's something else.

--- End quote ---
I can't answer for some. But when you charge the exterior capacitors, you create a current and potential difference in the middle one, which stores electrical energy at a rate of VI.

--- Quote from: hamster_nz on May 09, 2022, 11:02:33 pm ---Question still not answered:
Why do electrons in a wire drift proportionally to the current (the flow of charge), and not the energy being transferred?

For some the answer is : I'm not sure that they even drift

For others the answer for some here seem to be : Electrons carry not only charge they also carry the energy. They all have little backpacks they carry their electrical energy around it, and when a battery is connect or disconnect a battery they all quickly fill or empty their backpacks as required, sometimes over great distances, exactly at the time the connection is made or broken.

--- End quote ---
Mmh I'm not quite sure why you renamed potential energy into 'backpack', but if I were to explain electricity to children, I would consider it. Is potential a forbidden word now?
I'm curious how you see energy moving in vacuum. Is vacuum filling/emptying backpacks too? And giving to electrons/protons?
electrodacus:

--- Quote from: hamster_nz on May 09, 2022, 11:02:33 pm ---
--- Quote from: Naej on May 09, 2022, 09:21:38 pm ---which explains clearly that it is a theory dictating where energy flows, not experiments.
Much like bsfeechannel, they don't point to experiments, because they cannot.

--- End quote ---
LoL.  Here's two experiments that show where energy flows.

Experiment 1:
Attached a transformer to 220V AC, and get (say) 9V AC @ 0.5A out the other side.  The wires never touch (due to insulation). How does that energy pass through the transformer?

The answer for some here seem to be : It can't. Because the energy flows in the wires. Those Watts coming out the transformer are not from the energy coming in.

Experiment 2:
Store energy into the middle of three capacitors in series. Energy is transferred even though no charges can pass around the entire loop. How is that possible?

The answer for some here seem to be : It isn't possible, because the energy flows in the wires. The energy in that middle capacitor isn't stored electrical energy, it's something else.

Question still not answered:
Why do electrons in a wire drift proportionally to the current (the flow of charge), and not the energy being transferred?

For some the answer is : I'm not sure that they even drift

For others the answer for some here seem to be : Electrons carry not only charge they also carry the energy. They all have little backpacks they carry their electrical energy around it, and when a battery is connect or disconnect a battery they all quickly fill or empty their backpacks as required, sometimes over great distances, exactly at the time the connection is made or broken.

--- End quote ---

Experiment 1:

You have two energy storage devices with magnetic coupling. Primary creates a magnetic field and the energy to create that magnetic field will either be returned to source if nothing is connected to secondary or it can be used by the secondary as it has access to the same stored magnetic field.
All energy flows through wires so if you have 9V * 0.5A = 4.5W power output then input power will be the same assuming ideal transformer so 4.5W / 220Vac = 0.02A
Energy is being charged and discharged multiple times per second.
But let me ask you this. Why if you apply DC to primary you can not get anything on the secondary ?  With DC you still have energy stored in the magnetic field when you connect the DC source and the magnetic field is still there so how come you can not transfer energy from primary to secondary ?
There will be a lot of energy wasted as heat in the primary with DC so energy travels through wire but you can not get any of that on the secondary as energy can only travel through wire (at least at this low potential).
 

Experiment 2:

Any number of capacitors in series will be seen as a single capacitor and energy will be divided between all those capacitors.
Energy flows only as long as it is needed to charge the capacitors and once the capacitors are fully charged no energy is flowing. None of that energy did any work so no heat or any other sort of radiation for ideal case and some amount of heat with resistance just for as long as the capacitors are not fully charged.

As for question still not answered. They were answered many times you just do not understand what energy is.
Not understanding energy, energy storage and likely much more makes you unable to predict what happens without running an experiment.

If the transfer of energy will have been possible efficiently without wires the there will be no expensive transmission lines.
You can transfer energy outside wires but that requires electrons or photons.
The youtube video I linked today about the electrostatic generator shows energy flowing both through wires and trough air. It is a special case due to very high voltages where air becomes a conductor but energy is not transferred by the electric field but by electrons that jump through dielectric in this case air and is excelentry presented in that video.
There are thousands of volts and small gaps that allows some energy transfer outside the wires in that applications but that space becomes a conductor at those voltages. Nothing like that is present in Derek's 20V and 1m gap experiment and all energy there travels through wires both during initial transient and in steady state DC.
hamster_nz:

--- Quote from: Naej on May 10, 2022, 12:40:24 am ---
--- Quote from: hamster_nz on May 09, 2022, 11:02:33 pm ---
--- Quote from: Naej on May 09, 2022, 09:21:38 pm ---which explains clearly that it is a theory dictating where energy flows, not experiments.
Much like bsfeechannel, they don't point to experiments, because they cannot.

--- End quote ---
LoL.  Here's two experiments that show where energy flows.

Experiment 1:
Attached a transformer to 220V AC, and get (say) 9V AC @ 0.5A out the other side.  The wires never touch (due to insulation). How does that energy pass through the transformer?

The answer for some here seem to be : It can't. Because the energy flows in the wires. Those Watts coming out the transformer are not from the energy coming in.

--- End quote ---
Perhaps it's what they say.
What I say is that you get 4.5W consumed in the input, 4.5W produced in the output wires.
Potential is converted into momentum in the primary, this increases the momentum in the secondary which is then converted into potential (9V).

--- End quote ---

How is that momentum transferred? When a marble rolls past a stationary one, the stationary one doesn't just start moving. Do the charges have little sticks that the prod each other with?


--- Quote ---
--- Quote from: hamster_nz on May 09, 2022, 11:02:33 pm ---Experiment 2:
Store energy into the middle of three capacitors in series. Energy is transferred even though no charges can pass around the entire loop. How is that possible?

The answer for some here seem to be : It isn't possible, because the energy flows in the wires. The energy in that middle capacitor isn't stored electrical energy, it's something else.

--- End quote ---
I can't answer for some. But when you charge the exterior capacitors, you create a current and potential difference in the middle one, which stores electrical energy at a rate of VI.

--- End quote ---
How does that current and potential get into the middle capacitor? And what what is current times potential, if it isn't energy?


--- Quote ---
--- Quote from: hamster_nz on May 09, 2022, 11:02:33 pm ---Question still not answered:
Why do electrons in a wire drift proportionally to the current (the flow of charge), and not the energy being transferred?

For some the answer is : I'm not sure that they even drift

For others the answer for some here seem to be : Electrons carry not only charge they also carry the energy. They all have little backpacks they carry their electrical energy around it, and when a battery is connect or disconnect a battery they all quickly fill or empty their backpacks as required, sometimes over great distances, exactly at the time the connection is made or broken.

--- End quote ---
Mmh I'm not quite sure why you renamed potential energy into 'backpack', but if I were to explain electricity to children, I would consider it. Is potential a forbidden word now?
I'm curious how you see energy moving in vacuum. Is vacuum filling/emptying backpacks too? And giving to electrons/protons?

--- End quote ---
Here are my incoherent ramblings...

For electrostatics, the electric field fill the universe (just like gravity does). And the location of charges in that field define the electric field, just like how the location of masses define the gravitational field.

In a wire, where charges can move freely, changes drift to where they see the local field leading them, like marbles rolling down into a valley under gravity. They don't need to 'know' that there is a battery that is 10cm away to know which way to go, they just mindlessly follow the slope of the local electric field. Exactly like how water finds it's way to the outlet of a lake or dam. And as they move, their location also contributes to the electric field.  Because charges are able to freely move within the wire, and their location defines the electric field, the electric field quickly becomes flat inside conductors when modest currents are flowing. The charges are not dissipating much energy, they are "doing minimal work" in the physics sense (force x distance).

At the edges and outside of the wires, where the charges can't freely move is where all the tension in the electric field occurs - that is where the fields have the most 'slope'. It is on that slope where you can extract energy from the fields. If you release a charge on such a slope it will know which way want to go - a negative charge will head in the "most positive" direction, and a positive charge will head in the "most negative" direction. If you were able to put an extra charge into a wire not much will happen - it will just drift along on the current.

You attach one end of a resistor to a just the positive wire, but leave the other end free. A small amount of charge will flow into it, but very quickly the whole resistor will have an flat electric field, just as flat as the wire. Anywhere you measure with a voltmeter on the either resistor or the wire will measure 0V. The resistor isn't releasing any of the field's energy, just moving where the field's energy is in space.

But when you attach one end of the resistor to a positive wire. and the other end to the negative wire, then you can extract energy from the field. All the semi-mobile charges in the resistor will see the "so many volts per meter" slope of the field and start moving in that direction. Those charges don't need to know how the electric field gets there, just that the field is there, and it has to follow it. This converts electrical energy into momentum of the charge.

Because the slope in the resistor is so high compared to that inside the wire, they really want to move fast. This gives the thermal heating (or light from the light bulb). That energy isn't coming from the electrons moving in the wire, but the slope in the electric field that is through the resistor, that is what accelerates the charge.

The wire supplies a steady supply of low-energy electrons to be accelerated in the resistor, and removes the low energy electrons that appear at the resistor's other end. The charge is accelerated using the energy supplied by the field, not the wire.

All this time, (assuming resistance of the wires is low compared to the resistor the wires) the electric field on the inside of the wires is flat, and the charges in the wire only transfers minimal energy. The wires set the shape of the electric field, and supplies charge, but the energy flows in the fields.

Batteries also change the shape of the electric field. They generate (and try to maintain) an electric field between their terminals. Batteries are sold as X volt batteries. The first thing you care about for a battery is the strength of the electric field it generates between its terminals. The total energy it can supply is a secondary consideration (along with size or cost). When you connect a battery to a wire, because the wire's charges are mobile the electric field around that wire changes to match that of the battery's terminal. And sure, some charge movement is required for this, but if you could look at how much charge moved how far to build up the electric field it is minimal. (That is unless somebody has put a large capacitor in there somewhere...)
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