The force between the plates of a parallel plate capacitor of capacitance '$$\mathrm{C}$$' and distance of separation of the plates '$$\mathrm{d}$$' with a potential difference '$$\mathrm{V}$$' between the plates is

A battery is used to charge a parallel plate capacitor till the potential difference between the plates becomes equal to the e.m.f. of the battery. The ratio of the energy stored int he capacitor to the work done by the battery will be

Capacitors of capacities $$\mathrm{C}_1, \mathrm{C}_2$$ and $$\mathrm{C}_3$$ are connected in series. If the combination is connected to a supply of '$$\mathrm{V}$$' volt, then potential difference across capacitor '$$\mathrm{C}_1$$' is

The plates of a parallel plate capacitor of capacity '$$\mathrm{C}_1$$' are moved closer together until they ant half their original separation. The new capacitance '$$\mathrm{C}_2$$' is