why can the capacitor be charged by a battery (DC)

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Matador

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I believe that denying that current passes in, via, through, whatever, a capacitor because the electrons are stopped at one armature (plate) is a somewhat ayatollesque position.
It's also interesting that people don't seem to have the same philosophical issue with a transformer. We take it for granted, that a magnetic field induces a current so long as it's changing. A changing current flowing through a primary will magically appear at the secondary (all other things being equal), and that happens via the transformer. However it's not like the electrons are flying across the air gap.

Instead, it's the changing (magnetic) flux that's inducing/transmitting the energy across the secondary, just like it's the changing (electric field) flux that's inducing/transmitting the energy across the terminals of the capacitor, and both are the result of charges in motion, and both are equivalent to electrons moving in a wire. The idea that magnetic fields induce electric fields (and vise versa) is what allows electromagnetic waves to propagate.

I would go so far as to say: if you believe that "current" is only the movement of electrons in wires, then you also don't believe that radios can work.
 

Newmarket

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It's a microscopic definition, which justifies one's position of saying that current doesn't pass through because there's an insulating material.
On a macroscopic level, which IMO is what most members are concerned with, current passes via a capacitor, so it can be modelled as a dipole with an impedance.
I believe that denying that current passes in, via, through, whatever, a capacitor because the electrons are stopped at one armature (plate) is a somewhat ayatollesque position.

Hi. I think you're misunderstanding what I mean by "Net Flow" or I am not articulating it properly.
I am absolutely not saying "that current doesn't pass through because there's an insulating material"
Of course "current", as opposed to individual electrons, flows, to quote you " in, via, through, whatever, a capacitor" as you have well illustrated . Particularly with your comparison of circuits with/without capacitor.
 

abbey road d enfer

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Hi. I think you're misunderstanding what I mean by "Net Flow" or I am not articulating it properly.
I am absolutely not saying "that current doesn't pass through because there's an insulating material"
Of course "current", as opposed to individual electrons, flows, to quote you " in, via, through, whatever, a capacitor" as you have well illustrated . Particularly with your comparison of circuits with/without capacitor.
Some misunderstanding on my part here. I fully agree with your analysis. I'll try to rephrase and edit my post. I was trying to stand on your shoulders.
 

Newmarket

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Some misunderstanding on my part here. I fully agree with your analysis. I'll try to rephrase and edit my post. I was trying to stand on your shoulders.

No problem. tbh the word "ayatollesque" made me smile :)
I could have expanded more but just wanted to make a concise statement and not go over ground that, imo, had already been well covered.
I can understand your sort of frustration at the questioning of well established electrical/electronic models and concepts. I'm not saying that established concepts can never be challenged but if they are it should really be in contention for a Nobel Prize / Oxbridge Chair (or I guess Harvard or MIT if in North America) rather than a niche internet community :).
And tbh I was glad that no one was asking me to expand on Holes etc - because I was just grabbing a quick reply as 'light relief' from the paid work (HV Systems for Semiconductor Applications) and not really having the time to go down the route of Minority Carriers ; Drift Velocity etc...
All Good. Cheers.
 
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moamps

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I was hoping that this discussion would stop before you bring it down to a personal level by mockingly calling me an “esteemed member” but also a proponent of some insane “ayatollesque” position.

Anyway, I am happy that this discussion has evolved from a completely unacceptable point of view (not to say worse) presented here:

1633172940971.png

to this nevertheless acceptable position here:

1633172985662.png

However, I would always prefer to call this "current via a capacitor" a signal.
It is not necessary to go to MIT to understand everything together, nor is there any reward for that.

Having already mentioned the "holes", before analyzing the Ebers-Moll model and the tunnel diode at the end (Leo Esaki won the Nobel Prize for this), I would like to ask what the position is whether the holes are positive charge carriers in semiconductors or just models that describe the absence of electrons in the crystal lattice, or something third?
 

abbey road d enfer

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I was hoping that this discussion would stop before you bring it down to a personal level by mockingly calling me an “esteemed member”
I think you're overreacting. Esteemed is not an insult, AFAIK? It is actually what I think, and there's not an ounce of irony in it, believe it or not.
If you feel insulted, pIease accept my apologies.
I have come to appreciate your knowledge, but I think it comes with some kind of narrowmindedness. And I won't apologize for writing that.
Remember you tried to prove that a Çuk converter could not work? My position was that if someone sold it, it may very well work. that makes me a little more open-minded.


but also a proponent of some insane “ayatollesque” position.
Insane is your own word. Please see next post.
Since it's more than 50 years that I left school, I tried to refresh my memory, thanks to the internet. It turns out that most of the pages adopted the concept of current passing through capacitors.
You can say that current on one armature is reflected in the other, but at the circuit analysis level, considering it passes through is simple and effective, and can be verified in practice. Whatever happens at quantum level is out of the scope of this group.
View attachment 85190

However, I would always prefer to call this "current via a capacitor" a signal.
This is not the common acceptance of the word signal, when almost everybody working in electricity/electronics understands what "current passing through" means.
Signal is almost universally understood as a more or less complex voltage or digital info. Although current loops cannot be ignored.

Having already mentioned the "holes", before analyzing the Ebers-Moll model and the tunnel diode at the end (Leo Esaki won the Nobel Prize for this), I would like to ask what the position is whether the holes are positive charge carriers in semiconductors or just models that describe the absence of electrons in the crystal lattice, or something third?
I am not the one who mentioned holes. I don' play golf. And I'm no Nobel prize.
Actually, what's been taught to me was the second option, but it may be proved completely wrong in the light of science advances in 50+ years.
I have no doubt "something third" is cooking. If you have insider info, give us a scoop!
 

sahib

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@ Moamps.

No apology necessary.

I was approaching the argument from ESR angle for AC flow.

Abbey finalised the argument and no need to go further.
 

MisterCMRR

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I've only read the beginning (technical) part of this thread, but I feel compelled to correct a very common mistake in the way a transformer is explained. In the primary (the driven winding of a transformer, by definition) the current flow generates a proportional magnetic field. However, when this changing field cuts across a conductor in the secondary, a proportional voltage is induced in it. Think about it - if a current were induced in the secondary, an unloaded secondary winding would produce infinite voltage!

I explain the operating principles of transformers in the chapter I wrote for "Handbook for Sound Engineers" - available for free at
 

Newmarket

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In my country, not so far from yours, the word has passed in the common language; I understand that it may be perceived as violent or very derogatory.
Please suggest a more PC term.

I suppose there are sensitivities with it and it might be taken that way although I think the common usage you refer to is the case for many people.
It seems to communicate concisely in the context you used. I would think that any substitution would properly require a whole sentence in itself.
I don't think it's so widely used here (UK) but that's probably due to different international and historic links - basically British Empire vs French Empire.
I'll decline to offer alternatives :rolleyes:
 

Newmarket

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Having already mentioned the "holes", before analyzing the Ebers-Moll model and the tunnel diode at the end (Leo Esaki won the Nobel Prize for this), I would like to ask what the position is whether the holes are positive charge carriers in semiconductors or just models that describe the absence of electrons in the crystal lattice, or something third?

I think it was me who mentioned "Holes" if you mean in this thread.
I'd say that the two 'options' you give are both valid and not mutually exclusive.
Although I find the term "just models" a bit dismissive.
"Models" are really all we ever have and particularly so at the particle level .
You could equally well say ,in the first case, that "the holes are modelled as positive charge carriers..."
 

Newmarket

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It's also interesting that people don't seem to have the same philosophical issue with a transformer. We take it for granted, that a magnetic field induces a current so long as it's changing. A changing current flowing through a primary will magically appear at the secondary (all other things being equal), and that happens via the transformer. However it's not like the electrons are flying across the air gap.

Instead, it's the changing (magnetic) flux that's inducing/transmitting the energy across the secondary, just like it's the changing (electric field) flux that's inducing/transmitting the energy across the terminals of the capacitor, and both are the result of charges in motion, and both are equivalent to electrons moving in a wire. The idea that magnetic fields induce electric fields (and vise versa) is what allows electromagnetic waves to propagate.

I would go so far as to say: if you believe that "current" is only the movement of electrons in wires, then you also don't believe that radios can work.

Yes. It did occur to me that there is some comparison to be made with transformers.
But I think the difference is that you can "see" complete circuits on both the primary and secondary sides.
And since the transformer winding itself is 'just' a long wire in dc terms then it might appear not to give rise to the same conceptual problems.
Of course, it's quite likely that the input signal is capacitor coupled !
Having said that I don't think many people have the difficulty with the concept of current flowing through a capacitor that is being discussed here tbh.
 

Matador

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I'm guessing nobody wants to re-visit this, but in the time since this discussion here, the YouTube channel Veritasium just did a great video on this very subject, which completely explains the concepts of energy flow through wires (or lack thereof), and why 'flux' flows through/via a capacitor as well as a transformer.

 

moamps

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the YouTube channel Veritasium just did a great video on this very subject, which completely explains the concepts of energy flow through wires (or lack thereof), and why 'flux' flows through/via a capacitor as well as a transformer.

For sure.



 

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