The function of capacitors in a circuit is often explained with comparison to a water tank. When a capacitor is compared to a water tank, the battery can be considered as the pump filling the tank with water.

On the circuit, water is similar to dislocation, and the water quantity in the tank can be expressed as the changed quantity pumped in to the capacitor. Thus, the capacitor’s area corresponds to the dislocated quantity as the tank’s area corresponds to water quantity.

We know that a long and narrow vertical tank can hold just as much water as the short, wide and horizontal tank can. However, the vertical tank has more pressure due to the water than the horizontal one. In the same idea, we can think that for a large capacity, there is a low voltage, and short and wide capacitor, and for a low capacity, there is a high voltage, and long and narrow capacitor.

When the capacitor is connected to the circuit while receiving energy from active components(Battery), one electrode of the capacitor bears a positive electric charge, and the other electrode becomes negative. The electric charge on the electrode will conduct the opposite charge on the whole. The electric charge conducted like this is called Permittivity.