I have it figured out. The attached explains everything.
Ron
we all know DC gets blocked and AC passed when going through a capacitor. Assuming an AC signal propagating through a cap, can anyone explain specifically the flow of electrons acting on the capacitor which hence allows the signal to be passed through? just curious all this while. Couldn't find any book/site which specifically explains why this happens.
... It is wrong to say that a capacitor is "charged". You should instead say the capacitor is energized ...
Ratchit;956221 A capacitor is a specific electrical energy storage device. It stores energy by separating charge said:energized[/B] when the charge on the two plates are unbalanced, and a voltage appears across the capacitor. Current exists in the series circuit that contains the capacitor, but no charge goes through a capacitor unless there is leakage. The charge accumulates on one of the plates and depletes equally on the other to make a net charge of zero. Again, the capacitor does not charge, it instead energizes. When the voltage appears due to the charge accumulation and depletion of the plates, it opposes the energizing voltage. When the energizing voltage equals the capacitor voltage, no more charge flows in the capacitor circuit. That is why the charge flows temporarily in a capacitor circuit when a DC voltage is applied, and later slows up and finally stops when the opposing voltage equals it. Therefore, an AC voltage can cause a current to exist back and forth in a capacitor indefinitely, while a DC voltage is stopped after the capacitor is energized to its applied voltage.
Ratch
I have it figured out. The attached explains everything.
Ron
qtommer,
A capacitor is a specific electrical energy storage device. It stores energy by separating charge, which in turn causes an electric field to form. Since all electric fields are a form of energy. It is wrong to say that a capacitor is "charged". You should instead say the capacitor is energized when the charge on the two plates are unbalanced, and a voltage appears across the capacitor. Current exists in the series circuit that contains the capacitor, but no charge goes through a capacitor unless there is leakage. The charge accumulates on one of the plates and depletes equally on the other to make a net charge of zero. Again, the capacitor does not charge, it instead energizes. When the voltage appears due to the charge accumulation and depletion of the plates, it opposes the energizing voltage. When the energizing voltage equals the capacitor voltage, no more charge flows in the capacitor circuit. That is why the charge flows temporarily in a capacitor circuit when a DC voltage is applied, and later slows up and finally stops when the opposing voltage equals it. Therefore, an AC voltage can cause a current to exist back and forth in a capacitor indefinitely, while a DC voltage is stopped after the capacitor is energized to its applied voltage.
Ratch
This is close to the worst explanation of a capacitors operation I have ever seen.!
You state that a capacitor is energised, yet you explain the operation of the circuit using charge to do so.???
Good luck with that!
I think your sig line says it all:
pe·dan·tic
–adjective
1.
ostentatious in one's learning.
2.
overly concerned with minute details or formalisms, especially in teaching.
The point that gets missed here though is that we usually prefer to use the simplest most straightforward abstraction, not the most real.
I was taught as a simple understanding that when you charge a cap current flows through it one way, then you discharge the cap current flows the reverse way.
It you attach it to AC it is constantly charging and discharging, and constantly allowing that AC current through it both ways.
And an AC signal (like audio) passes through the cap (as current) for exactly that reason.
MrAl,
I believe the point I was trying to make was that the descriptive word used was a misnomer.
Ratch
Well that's funny because you are arguing that "charge" is not as good a word as "energize" yet "charge" is less ambiguous than "energize" is.
We can "energize" a component but that says nothing about whether or not it will hold that energy or dissipate that energy. So which is it?
Are you going to try to stop me from "energizing" my light bulb?
Charge a capacitor and then disconnect it. Is it still energized?
In each of these tell me what i am really doing...
I am going to charge my car battery. (pretty clear)
I am going to energize my battery. (am i going to electrically energize it or mechanically energize it, or chemically energize it?)
It just so happens that i have a black box with two wires coming out. I am going to energize it. (did i make it do something like move, or did i store energy in it?)
It just so happens that i have another black box with two wires. I am going to charge it. (did i make it move or did i store something in it?)
Another black box known to be an electrical component with two wires. I energize it. Later, i connect the two wires to a light bulb. Does the light bulb light up or not?
Another black box known to be an electrical component with two wires. I charge it, or even "i charge it up". Later, i connect it to a light bulb. Does the bulb light up?
When we say "charge" we know pretty much what is happening. When we say "energize" we cant be quite as sure.
Let us now "charge" a capacitor. Current flows THROUGH the capacitor.
In the integral, we show that something accumulates (sums).
We then disconnect the capacitor and connect it to a resistor. What flows out of capacitor? We can say energy, we can say current, or we can say charge. If we say "energy" we dont know how much current is flowing. If we say "current" we know right away what is happening. If we say "charge" we really mean to say "moving charge" but we drop the 'moving' for short.
The capacitor stores energy in it's field, yet we say it is charged for short.
The inductor stores energy in it's field, but we dont refer to that many times and we also call that charged too.
Agreed, or disagree with any of this?
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