# capacitor plate voltages

Discussion in 'General Electronics Discussion' started by electronicsLearner77, Jul 27, 2015.

1. ### electronicsLearner77

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Jul 2, 2015
I was curious to know if it is possible to maintain the plates of a capacitor at different voltages, I mean to say one plate I will connect to one source and the other plate to other voltage say 5v and 3v. Stupid question but want to know.

2. ### Minder

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Apr 24, 2015
It happens all the time in many different circuits, when passing an AC portion of a signal for e.g.
I assume the voltages you show are a DC source.
If electrolytic, the polarity must be observed.
M.

3. ### AnalogKid

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Jun 10, 2015
And, both power sources must be connected to a common ground or reference potential.

ak

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4. ### Laplace

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Apr 4, 2010
It is the nature of a capacitor to maintain a constant voltage between its plates. The only way to change the voltage between the capacitor plates is to force a current to flow through the capacitor. But when we say that current flows through a capacitor we do not mean that charge moves through the dielectric insulator, rather that current flows into one terminal and an equal current flows out the other terminal. The charge itself accumulates on one plate and depletes on the other plate while an electrostatic field is generated in the dielectric between the plates. The field strength (and the capacitor voltage) is proportional to the degree of charge imbalance.

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5. ### electronicsLearner77

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Jul 2, 2015
This I was talking in the context of multivibrators where if one side of the capacitor plate changes voltage the other side also tries to match with it to maintain equilibrium. Is it correct?

6. ### Laplace

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Apr 4, 2010
It is true that the voltage across the capacitor cannot change instantaneously. If the circuit forces one side of a capacitor to switch to a new voltage level then the same change in voltage will be reflected on the other side of the capacitor as well. It will depend on the circuit what current may then flow through the capacitor to change the voltage across the capacitor.