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If a capacitor is connected to a battery and is charged, are there charges inside the wires or do they just accumulate on the surfaces of capacitor?

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A charged capacitor is not electrically charged but is electrically neutral. To charge a capacitor, free electrons are removed from one plate while being added to the other. electronics.stackexchange.com/q/35556 –  Alfred Centauri Apr 12 '13 at 17:48
    
still you can ask how are they distributed –  richard Apr 12 '13 at 17:50
    
@AlfredCentauri: We can always charge one plate of capacitor and leave the other neutral or charge it differently ;-) (not with a battery, of course). –  Vladimir Kalitvianski Apr 12 '13 at 21:19
    
@VladimirKalitvianski, you are of course correct. And, if the context were not that of electric circuits but, say, the "physicist's capacitor", then your observation would even be relevant ;-) –  Alfred Centauri Apr 12 '13 at 22:13
    
@VladimirKalitvianski, seriously though, the point of my original comment was to emphasize that, when we say a capacitor is "charged", we don't mean electrically charged, but energy "charged", i.e., the capacitor can supply energy to a connected circuit. Now, let's say that we did as you suggest and placed charge on one plate of a capacitor. Then, connect a wire between the plates. It would then be the case that the capacitor is no longer "charged" even though it would be electrically charged, i.e., non-neutral. –  Alfred Centauri Apr 12 '13 at 22:50
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2 Answers 2

Yes, the surfaces of the capacitor have a net negative or positive charge. The wires are also slightly charged because they also have a very small capacitance, but this is usually neglected.

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The ideal capacitor contains charge only in the plates and the charge distribution is uniform. In reality though :

1.The charge distribution is not uniform, the edges having more charge density.

2.The induced field is not perfectly uniform

3.There is always charges on the wires (they carry current) but that does not affect the net capacitence

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