Charging a Capacitor:

The voltage across the capacitor is not instantaneously

equal to that of the voltage across the battery when the

switch is closed. The voltage on the capacitor builds up as

more and more charges flows onto the capacitor until the

battery is no longer able to "push" any more charge onto

the capacitor, at which point the capacitor becomes fully

charged.

The initial flow of charges from the battery to the

capacitor means that there is a current flowing through the

system until the capacitor is charged. This current flow

decays exponentially from some initial value to zero.

DisCharging a Capacitor:

Switch remains open and voltage across capaciotr decreses

untill it reaches zero.