'...the same current
reaches the surfaces of both capacitors, lets put it that way.'
Plate charge is irrelevant, as is anything that happens inside an electronic component.
Current is clearly demonstrated from the OUTSIDE of the component, whenever the component has 2 legs and 1 amp is going in legA and 1 amp comes out legB.
I thank you and the professor for proving my case.
Back when I was playing around with F&P motors as wind generators my mate was putting CAPS in parallel with the 3 phase output. I went and put them in series and found when the CAPS weren't connected I was getting around 5 amps output. I connected the caps in series and got 9 amps output. So on my own testing YES current DOES flow thru CAPS.........................
I think we have to, as Mr Al said, agree to disagree on this issue. Time will tell.MrAl,
You did a good job of explaining why current must accumulate/deplete on the cap plates instead of going through the capacitor. That is the same argument I have been making. Who said that charge does go through the dielectric? If you re-read my posts you will find that I never said that.
ljcox,
Your explanation borders on mysticism. The Theory of Everything (TOE) is not going to rescue you from your belief that current may/is something other than a flow of charge. This is not a problem for theoretical physics. It is well known what happens when a capacitor is energized. The term "displacement current" may be a misnomer, but it is surely a representation of the changing electromagnetic fields that are in play when the energy storage level of a capacitor changes. As I replied to you in post #164 of this thread, "Until the different branches of physics are all unified, a theory of everything is just a musing of the mind. In any case, it will not change what the definition of current (charge flow per time) is. How do you know this? Are you psychic? If another quantity has to be defined, then that quantity will have a new name."
Ratch
What is there to wriggle out of?Hello again,
Well thank you Rachit, but wait till you hear this one, which im also sure you will agree with. This tops them all and offers no wiggle room for Brownout this time.
This is a direct quote, quoted from a lecture by Professor Viken, "Capacitors and Circuits Theory".
We enter the lecture while he talks about capacitors (two of them) in series...
Now keep in mind that these are not my words, these are the ACTUAL words of Professor Viken:
Notice how he goes through a LOT of trouble to avoid the use of the word "through" when talking about the current in the capacitor circuit.
(Note also there are no typos in this next passage, and so he does actually repeat himself a couple times)
"Two capacitors, connected together end to end in such a way that the same current,
they have the same current that, ah, goes (pauses) I shouldn't say that the same
current goes through them, because the current doesnt really go through a capacitor,
but i should say that the same current goes through, ah (pauses), the same current
reaches the surfaces of both capacitors, lets put it that way."
Sorry Brownout but i think you will have a very hard time wiggling around this one
Your explanation borders on mysticism. The Theory of Everything (TOE) is not going to rescue you from your belief that current may/is something other than a flow of charge. This is not a problem for theoretical physics. It is well known what happens when a capacitor is energized. The term "displacement current" may be a misnomer, but it is surely a representation of the changing electromagnetic fields that are in play when the energy storage level of a capacitor changes. As I replied to you in post #164 of this thread, "Until the different branches of physics are all unified, a theory of everything is just a musing of the mind. In any case, it will not change what the definition of current (charge flow per time) is. How do you know this? Are you psychic? If another quantity has to be defined, then that quantity will have a new name."
Ratch,ljcox,
How do I know this? I do know how current is defined now in this age. If you propose that current will have a different definition in the future, then it is up to you, the proposer, to show why the definition will change. And the evidence should be something other than a vague ability of a proposed theory to describe an already well explained phenomena. Energizing a capacitor is not rocket science, and there is no mystery about what is happening that needs an esoteric theory to explain.
Ratch
Bryan,well guys I was going to stay out of this thread but eh I just can't resist.
Back when I was playing around with F&P motors as wind generators my mate was putting CAPS in parallel with the 3 phase output. I went and put them in series and found when the CAPS weren't connected I was getting around 5 amps output. I connected the caps in series and got 9 amps output. So on my own testing YES current DOES flow thru CAPS.........................
As I have said before, we don't know what the Theory of everything will reveal.ljcox:
Well, the professor came right out and stated that current does not flow through a capacitor, and although he was tempted to say that it did, he always corrected himself. Why would he have to correct himself if it was ok to say that?
Brownout:
See reply for ljcox above. Also you need to watch his other lecture too.
ljcox:
Well, the professor came right out and stated that current does not flow through a capacitor, and although he was tempted to say that it did, he always corrected himself. Why would he have to correct himself if it was ok to say that?
I presume that terms & concepts such as current, current flow, charge and discharge, etc. were coined in the 19th century by people such as Gauss, Faraday, Maxwell, etc. These terms & concepts have been accepted by thousands of us since.
I daresay that they knew of the shortcomings of these terms and concepts.
I suspect that when the physicists derive the "theory of everything", some of these concepts & terms will need to be revised.
For example, if string theory proves to be correct, then current may be shown to be a flow of strings.
I say this because the concept of current flow being the flow of charge carriers does not cover the concept of displacement current.
I believe this concept is derived from Maxwell's equations which, as I understand it, show that there is a displacement current through the dielectric of a capacitor even though there is no flow of charge carriers inside the dielectric: note that the dielectric could be a vacuum.
This raises the question in my mind - why do we need a conductor to carry current?
Obviously the charge carriers in the conductor play a role of some kind.
I'll leave the answers to these questions to minds that are greater than mine.
The ends of the wire are points between which there is a 1 volt difference, and the resistance between those two points is .002 ohms. Why isn't there a 500 amp current between the ends of the wire? Isn't that mysterious?
You wrote "A theory of everything is not necessary to settle the issue of whether "...a current can only be defined as a flow of charge carriers". It's not a matter of theory; it's a matter of semantics".
I don't agree that it is semantics.
Nor do see why a "...a current can only be defined as a flow of charge carriers".
My point is that the Theory of everything MAY show that the flow of charge carriers is a consequence of something else that we don't surrently know about and it should hopefully resolve the paradox between conduction & displacement currents.
The electrician,
No, the inductive reactance is the primary inhibitor of current in this case.
I think you are agreeing with what I said all along. In a vacuum capacitor, no conduction current is present. But changing electromagnetic fields are present in the free space between the plates. These changing fields are physical, but can be calculated and interpreted mathematically as a virtual current. Would you agree with that?
Ratch
And you're missing my point about the TOE.
What I'm implying is that the "real current" may be something we don't yet know about & it is driving the charge carriers & it is passing through the dielectric.
I don't find it a paradox.I didn't miss your point; I just don't think it's very useful. I mentioned it originally as a possibility to see how readers would react. I certainly got a reaction.
How does this help us today? It doesn't. On could always postulate that some future increase in knowledge may explain something that seems paradoxical today. But is there really a paradox in the "definition" of "current" based on Maxwell?
There is no paradox when the modern point of view is used; it's the fields that count. The energy carried by an electric current is not carried by the charge carriers themselves; it's carried by the fields associated with the "current" as quantified by the Poynting vector. The relevant magnetic field can be due to a flow of charge carriers or due to a changing electric field. Either way, the energy resides in the fields.
Notice that the common D'Arsonval ammeter relies on the magnetic field to measure a current as does the clamp-on ammeter.
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