Same Charge Polarity Happening on Both sides of a Capacitor??

Dear Guys,

Here is a really fundamental and elementary question for you.

A- When you charge a capacitor with a DC voltage source, you see opposite charges accumulate on either side, and measure as such relative to your ground.

B- When you apply an ordinary AC sinusoidal signal with equal positive and negative peaks to the same capacitor, both scopes and simulators show simultaneously positive or negative voltages on both sides, with a slight voltage drop related to its reactive impedance Xc. Even when you take down frequency as low as 0.1Hz or 10 seconds each cycle, or change capacitor sizes between picos and micros same thing is observed.

Question:
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Shouldn't there be a 180 degree (pi radians, half a cycle) voltage phase difference across a capacitor when applied AC. When one side of the capacitor is at positive peak of the wave, shouldn't the other side be at negative peak?

No book, or web source I digged gave me a satisfactory explanation as to the Physics of what is going on here.

Can a few people take a stab at this glaring gap in my little electronics knowledge chain please? It is one of those painful ones that stops all progress in my head.

Thanks in advance for taking the time and effort to answer.

How can a capacitor be an inverter? A capacitor simply passes AC signals. If the reactance of the capacitor is too high because its capacitance is too low or its load resistance is too low then it will cause a phase shift of up to 90 degrees.

Only the voltage difference between both capacitor terminals (plates) matters, voltage relative to ground is irrelevant.

Audioguru said:

How can a capacitor be an inverter? A capacitor simply passes AC signals. If the reactance of the capacitor is too high because its capacitance is too low or its load resistance is too low then it will cause a phase shift of up to 90 degrees.

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Dear Mr. Guru,

To best of my knowledge "Inverter" is an electronics term do describe a device which converts DC power to AC. That is not subject of my humble question here. I am not disputing what is happening physically, just trying to understand how it is happening in physical level. Making assumptions and going on is not my strong suit. My head is created more like a physicist. Not comfortable with assumptions on such basic level.

A capacitor physically passes no current, no electrons, or holes. Accumulation of one charge polarity on a side creates an attraction for the opposite charge on the other side. Now, no matter what the frequency of charge change, or what size the component values are, it is a fair question to ask why are we not always seeing opposite charges on both sides, I believe.

Please see my attached pictures from DoCircuits simulation. When reactive impedance of the capacitor in the circuit is close to the ohm value of the resistor, we do see a 90d voltage phase difference between capacitor sides.

What I am looking for is a physical, visual explanation in terms of electron flow, why this phase difference is not 180d, or completely opposite at all times. Like when DC is applied to the same circuit. Try and see the event in those actual terms, not just calculus formula memorization terms please. You know, in my view looking at a physical event in terms of some old guys' formulas is not good enough. Those are just approximate human constructions. They do mislead people in many areas, and corrected rather frequently. I am sure they are perfectly correct in this simple case. But by themselves do not explain anything in actual physics. Sorry. opcorn:

No simulation circuit or other schematic attached, unfortunately.

I presume "inverter" in post #2 referred to an inverting amplifier. Did you already consider the point that capacitor charge is only set by voltage difference rather than absolute voltage? (Q = C*V, where V is the voltage difference between both terminals). So there's no 180 degree voltage phase difference, we are looking at a single voltage.

A capacitor physically passes no current, no electrons, or holes.

Click to expand...

A capacitor passes at least AC current. Electrons flowing into one terminal and out of the other terminal.

I have reliable electricity so I have never used a DC to AC inverter.
A digital logic inverter inverts the polarity of pulses so when its input goes high then its output goes low, and when its input goes low then its output goes high.
An analog inverter made from a transistor or opamp inverts the polarity of signals so when its input goes positive then its output goes negative, and when its input goes negative then its output goes positive.

Inverting the polarity results in 180 degrees of phase shift that one capacitor cannot do.