If the other side of the capacitor is truly isolated, then you will not get a net charge on the other plate. What will happen is that you will get a charge separation such that the electrons are either pulled toward the plate, exposing a positive charge further away, or they will get pushed away from the plate, exposing a positive charge at the plate. But you will not be able to put much of a charge onto the plate attached to the circuit because a voltage will quickly build up that will prevent further charge accumulation.

If the other side of the capacitor is part of a complete circuit, then a similar thing happens but now the electron that is pushed away can be carried along by the rest of the circuit or the electron that is pulled to the plate can be replaced by an electron coming from the rest of the circuit.

 

In the engineering field, there is a wonderful concept called abstraction. If you can abstract an otherwise complex device into something very simple to deal with, and that abstraction works for most of the applications, then why fight it? Only if the abstraction is too basic to account for some quirky behavior do you need a more complex abstraction. In the case of capacitor, the more complex behaviors that might need to be considered are series resistance, dissipation, inductance, and noise behavior. Charge movement inside the capacitor might account for some of these, but it is the behavior that needs to be explained, not the charge movement...

 

The formal mechanism that your looking for is called an charge attraction and repulsion.
This force is transmitted thru electric field lines.
Modern physics says that electric field lines are one dimensional lines that have polarity and direction.
Electrons or negative charge have negative polarity lines and radiate in, in every direction.
Protons or positive charge have positive polarity lines and radiate out, in every direction.
Without any medium, i.e. space.....these lines propagate at the speed of light.
With any medium we know of now....this propagation speed will be reduced and some field lines will be lost.
The strength of the lines is constant, but because it's a point source, the flux decreases with distance.
In other words, the difference between a 1 volt field and a 100 volt field is not the strength of the field lines......but the number of field lines.
Also field lines repel like field lines and attract unlike field lines.

This is very fundamental and should have been studied early in this subject.

I suggest that you study basic electricity(charge and current) and capacitor action.

After a good understanding of electric fields...........you might want to study magnetic fields.
They are harder to comprehend.

There we go. Now you're talking. It will take me a little while to research that. But, that is what I was looking for. While I do, perhaps one or more of you out there might be interested in this. (And no I don't work for them: [Moderator note: off-topic link removed]

 

in actual repairing of a lot of stuff, I dont have to worry about charge transfer and such. I know how capacitors act in a circuit and how to know if they are working or not. at home, I build a few things using tubes and solid state parts both. I found that a cap from plate coupling to base of a transistor has to be sized correctlyto prevent burning out the base when the hv plate supply comes on, due to the base side getting a big surge to charge up the cap. at the least, a big "pop"or thump wehn turned on.you should learn how the caps are supposed to act in the circuit and what specs they should have. worrying about the molecular or quantum level activity dosnt really help in the real world.

 

Well, that explanation will catch you up to the theory in 1862, hardly what I would call modern.

The modern theory of the electrical force is called Quantum Electro Dynamics or Q.E.D. If was developed over many years by scientists from Dirac to Feynman. It involves not fields and lines of force, which are a mathematical abstraction with no real existence, but electrons and photons, and the interaction of them in relativistic space-time. In Q.E.D. the force is carried by photons. which travel at the speed of light. It is considered the most accurate theory that Physics has ever come up with.

http://en.wikipedia.org/wiki/Quantum_electrodynamics


Bob

 

Thanks to all. Very informative and challenging. Feel free to continue, but I think I got the constructive direction I was seeking. (And polite too #)

 

Quantum theory oscillates between field theory and particle theory. A couple of years ago it was field theory.
Today there are back on particle theory. It will change again soon. Keep up to speed Bob.
Modern physics do not recognize a difference between a particle and a wave. A huge error. Because there is a huge difference.
I was trying to keep conversation in the electronic realm.
I have never heard of teaching on explaining capacitor action other than with electric field lines.
But I am old and maybe they are.

I have studied capacitors and the formal theory is very close, but not complete.

The two fields are always present and they always rotate.

 

I think we can safely put "simple" to rest now.

 

Sorry, but there is so much misinformation in that post I do not know where to start.

Electric field theory was complete with Maxwell's equations. And they pretty much work to explain everything that is needed for working out problems in electronics (until you get to the IC densities that exist today where QM is needed.)

Unfortunately, field theory predicts that atoms will collapse and a black body at any temperature above absolute 0 will radiate infinite energy.

That is why QM was developed. And nothing has oscillated back an forth since then. QM describes the world in terms of both particles and waves. The waves have become probability distributions rather than fields, and particles are spread out over space with no definite position.

But QM still had problems describing a complete theory of electronics. For instance, there is no magnetism, until you merge it with relativity, which is what Q.E.D. is. Q.E.D was finalized in the 1950s and has not changed substantially since.

Bob

 

In the engineering field, there is a wonderful concept called abstraction. If you can abstract an otherwise complex device into something very simple to deal with, and that abstraction works for most of the applications, then why fight it? Only if the abstraction is too basic to account for some quirky behavior do you need a more complex abstraction. In the case of capacitor, the more complex behaviors that might need to be considered are series resistance, dissipation, inductance, and noise behavior. Charge movement inside the capacitor might account for some of these, but it is the behavior that needs to be explained, not the charge movement...

It is a useful method, clearly. The Socratic method is also purported to be useful.

 

Unless a capacitor is incorporated in a complete circuit nothing much happens.

Charge and conductive electric current (which is made up of moving charge) cannot cross the gap between the plates or exist in the gap.

However a time varying signal (AC) can cross the gap and transfer energy from one plate to the other.

This is accomplished by changing the charge on one capacitor plate.
This change induces a change on the opposite plate.

If we now reverse the change on the first plate this induces a reverse change on the opposite plate.

So if we regularly change the charge on one plate and then reverse that change we induce a regular change of charge and reversal on the opposing plate.

This is a long winded way of describing alternating current.

The alternating current that passes through a capacitor is called the displacement current.
Its mechanism is quite distinct from the simpler conduction current that runs through wires and resistors.

 

It is a useful method, clearly. The Socratic method is also purported to be useful.

So I ask again, what real, measurable behavior of a capacitor doesn' t the Wiki model of a capacitor explain???

 

Bob,

Maxwell's equations are based on 3 experiments.

1. Coulomb's law......the electrostatic force between 2 static charges........INCOMPLETE....if either of the charges move.......the equation fails.

2. Ampere's law.....the magnetic force between 2 moving current elements.....INCOMPLETE....does not consider electric field movement.

3. Faraday law...induction......fairly complete and understood by Faraday, but not by his mathematic friends. Faraday was an excellent experimenter and physicist, but a poor mather.
Faraday had a much renowned mathematical friend write his equations for him. These equations were expressed with the electrical and the magnetic from 2 different frames of reference. Of course Faraday's experiments were conducted with the electric and the magnetic in the same frame reference.

This is what Maxwell had to work with. And this is why Maxwell's equations were never correct.

And you are right......a particle would collapse if it followed Maxwell. And you are right.....that's what started us down the rabbit hole called QM.

There was another experimenter.....the greatest experimenter, who redid all these experiments together. Only his equations properly expressed the relationship between the electronic and angular momentum. His name was Weber. Study Weber to understand.

If Maxwell would have used Weber's equations....we might be living on several planets today.

And if Maxwell's equations fail on particles.........why does it not fail on electromagnetic waves thru space. IT DOES FAIL.

Weber’s corrected equations work on plasma in the fusion reactors while Maxwell’s do not.
This corrected field theory work was done in the early 90’s.

From these equations, the true structure of matter has been discerned. All particles are rotating charge rings.

And with this structure......the universal force law has been derived.

There is only one physical entity and force in the universe.........charge.

 

Hello MikeML,
Your right...the spinning magnetic field on a capacitor plate or the spinning electric field on an inductor coil doesn't make much difference now. But as the frequency goes up and the length of action shortens....these rotations will be a large component of the signal and have to be accommodated. This is because the smaller you go......the stronger the rotation. At molecular distances......the rotation is so strong that it twists and delays field lines.
Again...this means that physical rotation at short distances can be stronger than fundamental electric and magnetic field force.
But for right now...it doesn't matter.
This is why Maxwell's equations work now.....but when you get down to it.....it's a Socratic method.

 

Bob,

Maxwell's equations are based on 3 experiments.

1. Coulomb's law......the electrostatic force between 2 static charges........INCOMPLETE....if either of the charges move.......the equation fails.

2. Ampere's law.....the magnetic force between 2 moving current elements.....INCOMPLETE....does not consider electric field movement.

3. Faraday law...induction......fairly complete and understood by Faraday, but not by his mathematic friends. Faraday was an excellent experimenter and physicist, but a poor mather.
Faraday had a much renowned mathematical friend write his equations for him. These equations were expressed with the electrical and the magnetic from 2 different frames of reference. Of course Faraday's experiments were conducted with the electric and the magnetic in the same frame reference.

This is what Maxwell had to work with. And this is why Maxwell's equations were never correct.

And you are right......a particle would collapse if it followed Maxwell. And you are right.....that's what started us down the rabbit hole called QM.

There was another experimenter.....the greatest experimenter, who redid all these experiments together. Only his equations properly expressed the relationship between the electronic and angular momentum. His name was Weber. Study Weber to understand.

If Maxwell would have used Weber's equations....we might be living on several planets today.

And if Maxwell's equations fail on particles.........why does it not fail on electromagnetic waves thru space. IT DOES FAIL.

Weber’s corrected equations work on plasma in the fusion reactors while Maxwell’s do not.
This corrected field theory work was done in the early 90’s.

From these equations, the true structure of matter has been discerned. All particles are rotating charge rings.

And with this structure......the universal force law has been derived.

There is only one physical entity and force in the universe.........charge.

"....INCOMPLETE....does not consider electric field movement." I like that. Like the Faraday you mention above, I'm not much for mathematics.

In my cursory internet research I found a couple things that seem relevant. Firstly, some seem to believe that Maxwell's so-called displacement current was an afterthought tacked on to his theory specifically because he couldn't explain how a capacitor works.

Second, I found it said that magnetic fields have nothing to do with capacitor action since a spherical capacitor works quite well even though all magnetic fields cancel out ( layman's terms).

I also read that if displacement current was really the answer, then there is no explanation for a vacuum capacitor in which no matter can propagate charge (push-pull) between the plates.

A little dangerous knowledge perhaps

 

So I ask again, what real, measurable behavior of a capacitor doesn' t the Wiki model of a capacitor explain???

Is any theory ever really "complete"? It seems they are all subject to supersedure.

 

Unless a capacitor is incorporated in a complete circuit nothing much happens.

Charge and conductive electric current (which is made up of moving charge) cannot cross the gap between the plates or exist in the gap.

However a time varying signal (AC) can cross the gap and transfer energy from one plate to the other.

This is accomplished by changing the charge on one capacitor plate.
This change induces a change on the opposite plate.

If we now reverse the change on the first plate this induces a reverse change on the opposite plate.

So if we regularly change the charge on one plate and then reverse that change we induce a regular change of charge and reversal on the opposing plate.

This is a long winded way of describing alternating current.

The alternating current that passes through a capacitor is called the displacement current.
Its mechanism is quite distinct from the simpler conduction current that runs through wires and resistors.

Then let me ask this: Imagine first a device in a vacuum that is creating an ac signal. It propagates that signal down a wire to one plate of a capacitor (also in a vacuum.)

The other plate is connected via a wire to a large, separate conducting plate. (Or non-conducting, I'm not sure here.)

Will the capacitor work? Or said another way, will the ac wave reach the destination plate and continue to oscillate there?

 

So I ask again, what real, measurable behavior of a capacitor doesn' t the Wiki model of a capacitor explain???

I didn't ask for measurable. I asked how the thing works to produce those measurement quantities. It's not a matter of the quantitative behavior or our description of the results. It's a question about the structure of cause and effect.

 

Thanks to all. Very informative and challenging. Feel free to continue, but I think I got the constructive direction I was seeking. (And polite too #)

Remember, I tried to drive a stake through the heart of this thread yesterday. I wash my hands of any chaos that may ensue.

 

Then let me ask this: Imagine first a device in a vacuum that is creating an ac signal. It propagates that signal down a wire to one plate of a capacitor (also in a vacuum.)

The other plate is connected via a wire to a large, separate conducting plate. (Or non-conducting, I'm not sure here.)

Will the capacitor work? Or said another way, will the ac wave reach the destination plate and continue to oscillate there?

First let me say that my last post to which the above quote is your response was the first of a two part explanation.
You haven't said if you followed the first part or not.

As to your question, you need to review it in the light of my first line:

Unless a capacitor is incorporated in a complete circuit nothing much happens.

It really depends upon how large your "large plate" is. You haven't constructed a complete circuit in your thought experiment unless the large plate is large enough to be considered as an earth. Then, if your generator is also connected to earth, the signal will pass the capacitor in the vacuum. This will happen whatever the large plate is made of.