I know that there is a $Vab$ between the plates but I know also that the charges attract each other in the inside side of plates. So, the questions are:
what happens when I just connect a wire on both plates before connecting the leads? Do the charges move on the wire? Why?
Is probably because I don't have anymore two infinite plates?
I think that this question can justify the overall question.
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Yes some charge from the plate will go into wire. Electric charge of same sign will expand to all available conductor surface due to repulsive force of the charge being stronger than the attractive force of the opposite charge (because that is more distant).
answered Feb 25, 2021 at 17:14
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$\begingroup$ But, in a capacitor the charges are concentrated only on the inside face of the plates so the charges are not aware if a cable is connected or not on the outside plate.What's wrong in my statement? $\endgroup$– FabioCommented Feb 26, 2021 at 11:26
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$\begingroup$ That is not true, some charge is also on the outer face. Charged particles on single plate are repelling each other, so while most of them are on the inner side (due to attraction from the other plate), some of them are on the outer side. Only in case of infinite capacitor is the outer side uncharged. Infinite capacitor is an idealization that does not exist. $\endgroup$ Commented Feb 26, 2021 at 12:09
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$\begingroup$ Perfect, so in an infinite capacitor is correct to say that the charges will not move, also beacause I cannot put the wire across the infinite plates, in all other cases they will move. Right? $\endgroup$– FabioCommented Feb 27, 2021 at 8:22
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$\begingroup$ I don't know what you mean by "put wire across the infinite plates". If you connect the plates with a wire, the charge will move and capacitor will discharge. $\endgroup$ Commented Feb 27, 2021 at 14:45
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$\begingroup$ I mean (buy the way, my question is just to understand the theory) if I have a capacitor with infinite plates is it correct to say that, since, as you also say, the outer side is uncharged, the capacitor will not discharge if I put a wire that connect the plates externally (where we have no charges)? Obviously this is not possible because the plates are infinite. $\endgroup$– FabioCommented Feb 28, 2021 at 15:42