# neutralize charge in series capacitors

I have a simple circuit as in the picture below. My question is why the negative charge -Q at the bottom plate of C1 moves and neutralizes with the positive charge +Q at the top plate of C2?

• The charges in the green circle are the same and should not be written as +/-Q. – Andy aka Dec 19 '16 at 10:41
• When one plate is charged to +Q, should the other plate also be charged to -Q? – anhnha Dec 19 '16 at 10:43
• The two inner plates in the green circle are at the same potential so there is nothing to move charges. – JIm Dearden Dec 19 '16 at 11:49
• Agree, but new problem now. Why there is no potential difference when there is a charge separation? – anhnha Dec 19 '16 at 11:50
• electric field. – Jasen Dec 19 '16 at 18:22

The area inside the green circle is electrically isolated from the rest of the circuit so there is always the same amount of charge inside the circle.

What charge flows into the top of C1, the same amount flows out of the bottom of C1 and into the top of C2, the same amount flows out of the bottom of C2, this is how capacitors work (or at-least a very good approximation)

Why does it move? Electric potential pushes it..