AC flowing through a cap. What actually happens?

[BrownOut]

The energy argument misses the point of conduction current/displacement current. The calculations only take into account the bulk capacitance and resistance, and ignore the distributed dissapation in the conductors, etc. So, it appears as though all the energy was accounted for, when in fact, it is not.

Then Brownout said that there is no displacement current between tanks "because there is no interaction between tanks". Well, not true. I said there was no displacement current, that's true, but i never said there was no 'interaction' There's a big difference. The changing water tanks would have a changing gravity field. Now are we to say that a changing gravity field generates a flow of *water* *through* the plexiglass plate panel?

There is no interaction, wether you say there is or not. The gravity field doesn't interact between the two tanks. One does not affect the other. To say the field "changes" does not imply an interaction, neither is that accurate, since near the earth's surface, the gravity field is constant. So then there would be no basis for postulating any 'normal' field that reacts, and thus no parallel can be drawn to the capacitor case.

 

[killivolt]

Here's a fun example with working components

Radio Waves & Electromagnetic Fields - Harmonic Motion, Radiation, Vectors - PhET

Click on the picture and download. Sort of fun to play with, it seems I have this before though by someone another ETO Member.

Enjoy, kv

Edit: Let's add another one.

https://phet.colorado.edu/en/simulation/magnets-and-electromagnets

 

[MrAl]

The energy argument misses the point of conduction current/displacement current. The calculations only take into account the bulk capacitance and resistance, and ignore the distributed dissapation in the conductors, etc. So, it appears as though all the energy was accounted for, when in fact, it is not.

It misses your point because you cant possibly have the level of current that you are suggesting. I provided the equations to start with so hey, if you're so sure of this then take those equations and build on them to show where the energy comes from and where it goes. Now's your chance to prove what you have been suggesting all along. What you are going to have to show is that somewhere, someplace, we get a lot more energy then the source is supplying. The energy you are suggesting has to be greater than the energy i showed being delivered by the source, so lets see where it comes from and where it goes. I'll believe almost anything if it is proved.

There is no interaction, wether you say there is or not. The gravity field doesn't interact between the two tanks. One does not affect the other. To say the field "changes" does not imply an interaction, neither is that accurate, since near the earth's surface, the gravity field is constant. So then there would be no basis for postulating any 'normal' field that reacts, and thus no parallel can be drawn to the capacitor case.

For one thing, who says we have to do this on earth? Lets do it in deep space where there are no stray gravity fields to bother us. Lets also make the pipes run far away from the tanks before they connect to the pump so they dont interfere too much either, not that that really matters anyway.
As the water changes depth the shape has to change which has to change the force of attraction between the two.
BTW, two bodies with mass do affect each other whether they are on the earth or not. I dont see how you could possibly think otherwise. What you seem to be suggesting now is that two bodies cant affect one another just because there is a third body nearby that might happen to be bigger than the other two. If the bodies get closer for example even the relative time changes for each of them.

 

[BrownOut]

It misses your point because you cant possibly have the level of current that you are suggesting. I provided the equations to start with so hey, if you're so sure of this then take those equations and build on them to show where the energy comes from and where it goes. Now's your chance to prove what you have been suggesting all along. What you are going to have to show is that somewhere, someplace, we get a lot more energy then the source is supplying. The energy you are suggesting has to be greater than the energy i showed being delivered by the source, so lets see where it comes from and where it goes. I'll believe almost anything if it is proved.

You haven't proved anything except that you can ignore parts of a circuit in an analysis that only estimates the energy, and make it look like you've accounted for all the energy when you haven't. I don't have to prove that the energy in the displacement field comes from anywhere, just as you don't have to prove the energy in the wire comes from anywhere. Both are not considered in your analysis, so then current must only flow in the reistor and capacitor, and not in the wire or in the vacuum, which of course, is not possible.

The energy I've suggested only has to be greater if we account for losses. In the displacement case, most of the energy remains in the system, just as it does in the case of conduction current in the wire. The proof is in Maxwell-Ampere, which says that the charge energy that flows in or out of a region ( the capacitor plate) is equal to the displacement current. So, no energy is lost or gained by the displacement current.

A simple way to think of it is the energy that flows through the system is neither lost not gained, so it doesn't affect the energy 'balence' in the equations.

For one thing, who says we have to do this on earth? Lets do it in deep space where there are no stray gravity fields to bother us. Lets also make the pipes run far away from the tanks before they connect to the pump so they dont interfere too much either, not that that really matters anyway.
As the water changes depth the shape has to change which has to change the force of attraction between the two.

What does the shape have to do with anything? If in fact there was some interaction, then you would have flow. But as I've said, water isn't charge, and there is no analog to displacement current in a water system. Although there may be an interaction due to static mass, there is no interaction due to the flow of the water current.

BTW, two bodies with mass do affect each other whether they are on the earth or not. I dont see how you could possibly think otherwise. What you seem to be suggesting now is that two bodies cant affect one another just because there is a third body nearby that might happen to be bigger than the other two. If the bodies get closer for example even the relative time changes for each of them.

Neither would affect the force of gravity they experience on Earth. In other words, gravity is the same on each body. If you are talking about the miniscule mutual gravity force that the masses have on one another, then there is still no interaction overall, since one vessle is empty at the end of the process. I suppose there would be a slight pull due to the mass of the container, but what of it?

 

[killivolt]

So, I will barrow the analogy to form my own.

2 Pumps 2 Tanks + 1 chain with individual links looping through one to next connecting the 2 Pumps. The 2 Pumps are exactly the same except for how they are driven both are centrifugal Pump and "Pump A will deliver power through the chain to Pump B"

Both pumps are primed in that what goes in will come out with a little loss, water cannot move through the pump except that it rotates.

The chain will move in a clockwise rotation with each twist link by link the power will end up from "Pump A" delivering power to "Pump B" with a little loss between all depending on how many links their are in the chain; you choose how many links it is; as this is just an example.

I have 60psi supply to "pump A" and a meter detection equivalent to "1gal" of water through the pump before it will shut off the 60psi supply at "1gal" only.

"Pump B" has a reservoir to the "side" as it's supply without pressure; then a "1gal" reservoir below it to capture it after the pump, a meter will be place after "Pump B" before the capture reservoir to measure how much water was actually moving through "Pump B".

We will measure the volume with meters of both pumps. One meter only for Brownout and both Meters for Mr,Al.

The chain represents EM field turning in clockwise rotation; the 2 pumps represent "Plate A and Plate B"

Now I open the valve "Pump A" turns and releases energy clockwise through the chain link by link until reaching "Pump B" it turns as well

Brownouts example: My interpenetration of the example "Pump A" moves "1gal" while "Pump B" moves "1gal" with a little loss to the chain and maybe is still inside each Pump.

Their is a pipe connecting "Pump A which flows directly into "Pump B" inlet and Pump B which has a receiving tank below for the useful volume is the sum from both Pumps into only "Pump B" reservoir and should be useful with it's total volume of "1gal +or- losses.

Mr,Al's example: My interpretation of the example will only allow "1gal" only by using both meters which are tuned to exactly divide the "1gal" between them before the supply is shut off. Depressible losses will reside in both sides.

Mr,Al's example has 2 receiving tanks with no pipe connecting the 2 reservoir's for the sum of both reservoir's will be the total volume is in each meter but the useful volume will be in "Pump B" reservoir's (The remaining volume is collected by "Pump A" reservoir) and is not useful.

Edit: I can see that it will not work if more than 1gal is being used. The only way you could get the volume of reservoir A to reservoir B by using an overflow with a connecting pipe that allows the water to move from reservoir A to reservoir B. However, once the pressure is shut off the remaining water in reservoir A will be only it's capacity to hold up to the overflow.

How am I doing?

Edit: I have looked at what I was trying to say and did some changes. Just to clarify by word association to what I want to communicate.

Last edited by killivolt; Today at 07:39 PM.

 

[MrAl]

killavolt:
Why two pumps?

You haven't proved anything except that you can ignore parts of a circuit in an analysis that only estimates the energy, and make it look like you've accounted for all the energy when you haven't. I don't have to prove that the energy in the displacement field comes from anywhere, just as you don't have to prove the energy in the wire comes from anywhere. Both are not considered in your analysis, so then current must only flow in the reistor and capacitor, and not in the wire or in the vacuum, which of course, is not possible.

The energy I've suggested only has to be greater if we account for losses. In the displacement case, most of the energy remains in the system, just as it does in the case of conduction current in the wire. The proof is in Maxwell-Ampere, which says that the charge energy that flows in or out of a region ( the capacitor plate) is equal to the displacement current. So, no energy is lost or gained by the displacement current.

A simple way to think of it is the energy that flows through the system is neither lost not gained, so it doesn't affect the energy 'balence' in the equations.



What does the shape have to do with anything? If in fact there was some interaction, then you would have flow. But as I've said, water isn't charge, and there is no analog to displacement current in a water system. Although there may be an interaction due to static mass, there is no interaction due to the flow of the water current.

Neither would affect the force of gravity they experience on Earth. In other words, gravity is the same on each body. If you are talking about the miniscule mutual gravity force that the masses have on one another, then there is still no interaction overall, since one vessle is empty at the end of the process. I suppose there would be a slight pull due to the mass of the container, but what of it?

What you had suggested with the displacement current is that it is somehow 'real', and that energy somehow gets from one plate to the other. That's a lot of energy to account for, and you cant use Ampere Maxwell because that doesnt prove that the displacement current is 'real', that's the point. The whole question is whether or not the displacement current is something real, and if it has no effect as you say, then it's not real right?
You can quote A.M repeatedly but it's not going to prove or disprove the truth about the main point of what we are seeking, nor is it going to prove that anything 'flows through' the cap which is what you said happens, and if anything does flow it's not anything that should be called current anyway. That's the point of the water-tanks experiment, even though it may not be set up perfectly as a really good analogy.

The elementary view of the force of gravity between two bodies of water in space (somehow without freezing of course) being attracted by their center of mass is not adequate for analyzing the situation between the two when they are changing shape. The calculation involves integration over the three dimensional shape and this becomes more important with objects that are closer together and objects that are somewhat randomly shaped.
But the whole point is to show that if the two systems were equivalent, we'd have to say that there is a flow of water between the two tanks that in addition to the water pumped through the pipe. Then we could say that (water) current flowed through the plexiglass separator. BUT, if we dont want to say that, we could still say that the calculation for the field normal to the gravity field made it look like there was current flow through the plexiglass. In other words, it would LOOK like the normal field was there because of the water flow if we took that perspective, when really the gravity field was responsible for the normal field.

 

[killivolt]

killavolt:
Why two pumps?

I couldn't see the active region as a pump between Plate A and Plate B. Rather, I wanted to see the active region as 2 pumps being the plates both Plate A delivering and Plate B receiving. The region between is the force e.g. EM Chain and links which I believe is really close to the EM field when you look at the links they are perpendicular to each other, with force applied it would transfer from link to link forward to the input of Plate B as would an EM field.

In a clockwise rotation as an EM field will result in the input power transfer to "Plate B" I want to show that their is a change of "state" from "Electron to EM Waves" with a torque then tension between the links until they reach "Pump B" and finally the transfer of energy the fluid. The fluid transfer with the force of a transitional energy that is split into 2 different carriers 1 is pressure from the chain and the other is fluid flow from the Pumps.

 

[Mr RB]

Mr Al, I think your "water in space" analogy is not a capacitor, mainly because there is no mechanism for displacement.

To simplify the argument, your water in space analogy works just as well regardless of how far apart the water tanks are. They could be on opposite sides of the galaxy.

If your analogy was sound, then a "vacuum capacitor" would work just as well if it had 2 plates very close together and would have the same capacitance and work just as well if the 2 plates were infinitely far apart.

That is not the case. A capacitor works (largely) because of the interaction between the plates, and any valid water analogy must take into consideration the interaction between the 2 water compartments. All valid "water capacitor" analogies must have the 2 water compartments interacting together in such a way, that a "displacement effect" can occur due to having an air tube between the tanks, or a membrane.

In both cases the air tube or membrane is a physical process (like fields/flux) in a capacitor and that physical process between the plates is real, and is very analagous to a "displacment current" as this physical process mimics the current in/out of the capacitor.

There is a real physical interaction between the 2 plates, and that physical thing could be called "displacement current" (although better terms may exist).

(edit)You could try an experiment based on what i said above;
Put 2 large plates (12" square PCB?) on opposite sides of the room in free air. Put an AC source between them and measure AC current (or just use a capacitance meter which will probably use a fixed AC freq source).

Now put the plates very close together and repeat the test.

"Displacement current" should be easy enough to detect.

 

[killivolt]

That is not the case. A capacitor works (largely) because of the interaction between the plates, and any valid water analogy must take into consideration the interaction between the 2 water compartments.

I made note of that in my analogy of Mr,Al's example their are 2 vessels holding the liquid, the EM field connection is the physical interaction between them and the amount of work being done is in each vessel reservoir's. Each having their own amount of water supply or as an example of a conductor the residing electrons to continue gathering to promote a working process.

valid "water capacitor" analogies must have the 2 water compartments interacting together in such a way, that a "displacement effect" can occur due to having an air tube between the tanks, or a membrane.

In both cases the air tube or membrane is a physical process (like fields/flux) in a capacitor and that physical process between the plates is real, and is very analagous to a "displacment current" as this physical process mimics the current in/out of the capacitor.

I'm not sure why the Links of my chain without torque cannot act as the (fields/flux)
EM will twist into the links and deposit the working mechanism to allow Plate B to begin churning out current flow equal to what went in.

is a real physical interaction between the 2 plates, and that physical thing could be called "displacement current" (although better terms may exist). (edit)You could try an experiment based on what i said above;
Put 2 large plates (12" square PCB?) on opposite sides of the room in free air. Put an AC source between them and measure AC current (or just use a capacitance meter which will probably use a fixed AC freq source).

Now put the plates very close together and repeat the test.

"Displacement current" should be easy enough to detect.

Again, I can't see that my Analogy will not satisfy it on all points. The chain can be as long as you want the physical Tanks can be moved apart or brought closer.

Edit: I can see that it will not work if more than 1gal is being used. The only way you could get the volume of reservoir A to reservoir B by using an overflow with a connecting pipe that allows the water to move from reservoir A to reservoir B. However, once the pressure is shut off the remaining water in reservoir A will be only it's capacity to hold up to the overflow.

 

[MrAl]

Hello again,


Killivolt:
Maybe you could draw a picture of your setup and post it?


MrRB:
It's not exactly a capacitor, but it has some of the same features.
Capacitor plates dont have to be close together to work. Classical theory has the fields extending to infinity.

Keep in mind that a vacuum capacitor does not have any physical material between the plates.

When you say 'interaction between plates' the only thing that can interact is the field, and the field is made up of virtual particles, which are said to not really exist.

The capacitors that are emulated with a 'membrane' are the dielectric type, not the vacuum type.

I thought i made it clear that we can not directly measure the 'displacement current', because as soon as you insert something between the plates it's not just a capacitor anymore, it's like two capacitors in series.
If we put a metal object in there it has free charges that can, due to the field, start 'flowing'. Otherwise, there isnt anything that can flow in there.

Let me quickly recap the main points:
1. Either current flows through a capacitor or it doesnt.
2. Either the so called 'displacement current' is real or it is not.

For 1 above we've established that charge does not flow through the cap already. Everyone agrees now i think. That leaves only the field, and the field doesnt have to flow to exist.
Another possibility is that the electrons are acting as waves through the capacitor, but then that would mean when they got to the other side they'd have to turn back into particles, and that would effectively mean the capacitor was shorted out.

See, if the displacement current carried any energy with it then the cap would get hot and we would see the capacitor drawing more current than it should have.

The whole point of the 'displacement current' idea was to be able to account for the B field when the conduction current was zero. It didnt come from trying to measure a current and then saying, "ok i know what the value of the current is now", and it DOESNT come from any conduction, it comes from a simple change in the field. In other words, we look at the B field when the conduction current is zero and then we wonder where that B field came from, and we find that the explanation is that the E field is changing. It's not 'because' of the 'displacement current', the 'displacement current' is because of the B field.

Let me put this another way. If you (or i or anyone else) totally forgot about 'displacement current' we would still be able to calculate everything we needed to in any circumstance. It's just an academic curiosity. If we all forgot about it right now, the only thing we would miss within any experimental setting would be the actual words themselves, "displacement current". Everything else would be perfectly fine. We'd still be able to calculate the B field, which was what this was all about.
In the water tank experiment, we dont need to think about any water 'flowing' from tank to tank except in the pipe line with the pump. We would still be able to calculate everything we needed, including the 'force' on each body. It's the same with the vacuum capacitor, we dont need any 'displacement current', we just need to know about the changing E field. Who cares if a constant times the changing E field value is in unit of amps? There's plenty of cases in physics where the units dont tell you ANYTHING about the workings of the situation.
Example, i would like to express my units for one experiment in "square inches per inch" (that would look like in^2/in normally). Anything wrong with that? What does that work out to be? Is it that simple?

 

[BrownOut]

What you had suggested with the displacement current is that it is somehow 'real', and that energy somehow gets from one plate to the other. That's a lot of energy to account for, and you cant use Ampere Maxwell because that doesnt prove that the displacement current is 'real', that's the point. The whole question is whether or not the displacement current is something real, and if it has no effect as you say, then it's not real right?
You can quote A.M repeatedly but it's not going to prove or disprove the truth about the main point of what we are seeking, nor is it going to prove that anything 'flows through' the cap which is what you said happens, and if anything does flow it's not anything that should be called current anyway. That's the point of the water-tanks experiment, even though it may not be set up perfectly as a really good analogy.

The elementary view of the force of gravity between two bodies of water in space (somehow without freezing of course) being attracted by their center of mass is not adequate for analyzing the situation between the two when they are changing shape. The calculation involves integration over the three dimensional shape and this becomes more important with objects that are closer together and objects that are somewhat randomly shaped.
But the whole point is to show that if the two systems were equivalent, we'd have to say that there is a flow of water between the two tanks that in addition to the water pumped through the pipe. Then we could say that (water) current flowed through the plexiglass separator. BUT, if we dont want to say that, we could still say that the calculation for the field normal to the gravity field made it look like there was current flow through the plexiglass. In other words, it would LOOK like the normal field was there because of the water flow if we took that perspective, when really the gravity field was responsible for the normal field.

Sure, A-M does prove that iD is real. It also proves that the net energy flow into or out of a region is balanced by the displacement current. So, just as in the conduction case, there is no energy gained or lost in the dispalcement current, so no extra energy has to be supplied by the battery. If that were not the case, then extra energy would also need to be supplied for the conduction current in the ( ideal ) lossless wire too. But since the wire component does not add or subtract energy, just as the displacement curent, we don't need any extra energy for that flow. ie.

energy lost in wire ( ideal ) = energy entering wire - energy exiting wire = 0
energy lost in vacuum id ( ideal ) = energy entering region - energy exiting region = 0.

So the battery needs only to supply the energy that's being captured in the E field of the capacitor, and the energy lost in the resistor. The other components of current do not add or subtract from the energy in the system, and so do no factor into the equation.

You keep saying something about the field normal to the gravity field for the water tanks, which doesn't make any sense. There is only a weak gravity field, no normal fields. In addition, the gravity field, as I've pointed out, is a static field due to static mass, and no field arises due to the current, so the situation is not equivalent, and thus not applicable to the capacitor situation.

 

[MrAl]

Sure, A-M does prove that iD is real.
.

You cant use something being brought into question as proof that it exists. That's just going to be endless repetition on your part. You need to find something new to bring into the argument.
For example, if we wanted to prove that Ohm's Law really works, we couldnt use Ohms Law to prove it because that is self fulfilling.
One thing we might do is to perform some experiments and compile data and try to draw some conclusions.
Another example, we cant use gravity to prove that the Higgs particle really exists. Instead we have to build multi billion dollar test equipment and run trillions of tests over a two year period and compile data and draw conclusions that either help us prove or disprove the Higgs.

 

[BrownOut]

Just saying something doesn't exist doesn't make it so. That's just going to be endless repetition on your part. The proof is in the mathematics and in expermental data. Once a law or principle is proved, it doesn't need to be proved over and over and over and over.... We've already designed many experiments to measure and prove iD. We've proved it from the standpoint of conservation of current. We've proved it from the standpoint of the continuity principle. The only reason for endless repetition is endless repetition of denial on your part.

 

[BrownOut]

So, I had some fun with my granddaughter. We took my "Fluke VoltAlert 1lac".


my granddaughter about the same.
"

Well, since you have a grand daughter, I'm presuming my guess that you are a freshman in college was way off.

 

[killivolt]

Well, since you have a grand daughter, I'm presuming my guess that you are a freshman in college was way off.

I thought you were just joking. Either way it was funny.

 

[killivolt]

Best I could do for the moment.

Hello again,


Killivolt:
Maybe you could draw a picture of your setup and post it?

Best I could do I thought I could explain it verbally. Hopefully you will get the picture.

Either way you have the pressure to create 2 different active regions while, their is a flow coming from the source to supply the flow and keep it moving.

 

[MrAl]

Just saying something doesn't exist doesn't make it so. That's just going to be endless repetition on your part. The proof is in the mathematics and in expermental data. Once a law or principle is proved, it doesn't need to be proved over and over and over and over.... We've already designed many experiments to measure and prove iD. We've proved it from the standpoint of conservation of current. We've proved it from the standpoint of the continuity principle. The only reason for endless repetition is endless repetition of denial on your part.

Well you're doing the same thing then
Also, you admit that there is no charge flowing through the cap, and the only thing left is the field, so what exactly are you saying is flowing through the cap then? If the displacement current isnt doing anything, who needs it?
In other words, what is it that you are trying to prove?
Also, are you still saying that "current flows through the capacitor"?
I think you should state what exactly you are trying to prove (or simply show) by posting here, in your own words.

 

[MrAl]

Best I could do I thought I could explain it verbally. Hopefully you will get the picture.

Either way you have the pressure to create 2 different active regions while, their is a flow coming from the source to supply the flow and keep it moving.

Hi again,

Oh ok, that's a decent drawing. What is that chain between pumps doing for us?

I think in my setup if we used a chain it would be between the two tanks, but i'll wait till you explain more.
In my setup, there is definitely gravitational attraction between the two tanks, so it though we could think of that as a 'field' even though relativity would tell us that space time has changed. The gravity (or spacetime) does not have the ability to pull the water through the side of the tank. The 'field' or 'influence' or warping of space time does exist, but that's all, as there is no water between the tanks. Quantum physics would probably tell us something like the probability of finding a water molecule between the two tanks is very very close to zero.

If we look at this another way, if we remove the phrase "displacement current" from the books we would not have lost anything.

Im thinking that the only real proof lies in quantum physics, because after all, the electron frequency is on par with the Plank constant, unlike say an elephant

 

[Mr RB]

...
Also, are you still saying that "current flows through the capacitor"?
...

Please let's not go back to that argument again! CURRENT and THROUGH are as much conceptual and theoretical as they are real, and in *many* of the most important cases in electronics it is a fact that current goes through, please see all my earlier posts on the subject.

I think what we agreed on was that any individual electron does not flow "through" from one plate to another ie; that there is (generally) no direct conduction between the 2 plates.

...
2. Either the so called 'displacement current' is real or it is not.
...

I think we may be arguing at cross purposes... Does anyone think that "displacement current" is direct conduction of electrons from one plate to another? Probably not, since your vacuum capacitor cleared that up pretty quick.

But as for "real", yes there is a physical process there. As evidenced by my "plate distance" experiment. If there was no REAL physical process occuring between the 2 plates then the capacitor would work exactly the same regardless of distance between the plates.

If you agree there is a real physical process occuring between the 2 plates as current is going into one plate and out of the other plate then I think we agree. You don't like that process to be called "displacement current" (based on your posts) but I don't really mind the term.

The reason I don't mind the term is because I think one of the most important fundamentals of electronics theory is current flow, and we need to be able to work with current flow THROUGH any 2 pin component (including capacitors) and "displacement current" is just a conceptual term that allows us to work with closed circuit currents.

 

[MrAl]

Hi again,

MrRB:
Well as i outlined several times there are different forums that will take a different view. The physical view is that there is no current flow THROUGH the capacitor, while the circuit theory view is that current is *assumed* to go through the capacitor. Note the word 'assumed'.

Let me restate where the discussion has taken us.
First, people were saying that "current flows through a capacitor", and i had said that in circuit theory you can assume that to make the equations work easier, but i also said that in the bottom line physical view that no current flows through the capacitor. We then divided the 'current' into two 'types', where one was the conduction current and the other was the 'displacement current'. We then went on to discover that the conduction current does not make it through the capacitor, so that leaves the displacement current. We then started to argue if the displacement current is real or not. Brownout said that he cant see something that is not real having a real effect.

So you see we are really at the place where we want to discover if the displacement current is a real current or just a byproduct of an equation. We know that we can 'assume' that current flows through the cap just for computational purposes, so we shouldnt have to talk about that anymore. As long as we remember that that is not what is really happening inside the capacitor.

Now the only argument left is about the displacement current, is it real or not. But there is also a side discussion to this, and that is even if it is real (somehow in some way) it has to be something that is not actually conducting because if there was any conduction it would consume power, but in any case we cant simply state that "current flows through a capacitor" because that would be very misleading. In the circuit theory case, yes, but not in the physical case. Circuit theory isnt always concerned with the internal operation of a device, while physics theory often is. So at the very least, we'd have to divide the discussion into two sections:
1. Circuit theory, and
2. Physics theory

There's no way around this.

So back to the displacement current....is it real or not?

When we look at the Maxwell equation (again) we see that it is an equation for calculating the B field. Note that it is not an equation for current. It takes arguments of current and change of E flux, and spits out B. That's because the whole problem began when there was an 'extra' amount of B field without any conduction current flowing. Hence we can calculate the extra B field knowing the change in E flux. NOTE that we dont even have to know what the 'displacement current' is, but we can still calculate the field, which is what we wanted to do in the first place. The units happen to come out to units of amps AFTER you multiply the change in E flux by a constant, but that's just units and units can be deceiving. I was trying to illustrate this with the water and pipes experiment, where the volumetric flow would have to have been in units of cubic meters per second (or similar). Another example, a little less direct, is in the result to a problem that comes out to "square inches per inch". I didnt see any comments yet on that BTW (he he) but sometimes the units will resolve into units of simply "inches" but other times we cant do that, we have to leave the units in "square inches per inch" even though it doesnt appear to make sense at first.

So anyway let me get back to the displacement current more directly....

We want to calculate the extra B, so we measure the current and we measure the change in E field, and there we go, we can calculate the B field. Note we dont measure the so called 'displacement current' now do we? Why not? If we want to calculate the B field then how in the world are we going to measure the displacement current in order to get the answer? It's simple, we dont. In other words, the displacement current doesnt do us any good. It doesnt really help to know that we have "I amps" of displacement current because who cares? The only people who care are those that would like to know if we can say that "current flows through a capacitor" or not. If the displacement current is real then there may be a desire to state that current flows through a capacitor, but think about what we would be saying. We'd have to skip all the details of how different this new type of current (if we can even call it that) is, and that would be misleading. So i guess the best thing to state then is current does not flow through a capacitor, but there's a fictitious current that is sometimes talked about that is almost equivalent to a current when it comes to the B field. Even that isnt perfect though.

So if you want to tell someone that current flows through a capacitor, then you should also explain the details of how whatever it is between the plates is not the same as what is in the wire. It wasnt called "displacement current" because it was the same thing as what was happening inside the wire leading to the capacitor, if it was it would have been called "capacitor current".

On the lighter side of things...

Anyone ever play that game "Indiana Jones and the Temple of (something)"? That's where the guy you maneuver around sometimes has to jump over three alligators all with their mouths wide open and snapping. That guy reminds me of an electron trying to jump across the mote (vacuum) over the hungry alligators. Does he ever make it to the other side?