Capacitance

Consider two conductors having equal but opposite charges +Q and –Q on them. There is a potential difference V between them. Such a system of conductors is called a capacitor. Experimentally it is found that the potential difference is directly proportional to charge on a conductor. As charge increases, the potential difference between them also increases but their ratio remains constant. This ratio is termed as capacitance of the capacitor.

C = Q/V

The capacitance is defined as the ratio between the charge on either of the conductors and the potential difference between them. It is a measure of the capability of a capacitor to store charge.

In SI system of units, capacitance is measured in farad (F). The capacitance is one farad, if a charge of one coulomb creates a potential difference of one volt.