The equivalent capacitance of the system shown in the following circuit is:

The distance between the two plates of a parallel plate capacitor is doubled and the area of each plate is halved. If C is its initial capacitance, its final capacitance is equal to

The effective capacitances of two capacitors are 3 $$\mu$$F and 16 $$\mu$$F, when they are connected in series and parallel respectively. The capacitance of two capacitors are :

A capacitor of capacitance C = 900 pF is charged fully by 100 V battery B as shown in figure (a). Then it is disconnected from the battery and connected to another uncharged capacitor of capacitance C = 900 pF as shown in figure (b). The electrostatic energy stored by the system (b) is