What happens to the voltage across a capacitor as it discharges?

well to get the answer first know the principle by which a capacitor(consider a capacitor without dielectric) gets charged .let a capacitor with plates p1 and p2 and resistor in parlell are connected to a DC source , when the switch is closed the circuit is in ON state and current starts flowing ,assume the flow of current as the movement of negative charges then the concept would be much clear.

assume that p1 is connected with positive terminal of the battery and p2 with the negative terminal ,now as the switch is closed the negative charge on p1 is attracted by the positive terminal of the battery and is driven to the other plate p2 of capacitor.as this process continues charge seperation increases and potential difference starts getting developed and after a very long time the potential diff. across capacitor becomes equal to the applied voltage V.

during discharging first of all we short the battery , this mplies that we are short circuiting plates p1 and p2 so again charge redistribution takes place and after a longtime both the plates become electrically nuetral