A device used to store an electric charge, consisting of one or more pairs of conductors separated by an insulator is called Capacitor.
A capacitor is a passive two-terminal electrical component that stores potential energy in an electric field. The effect of a capacitor is known as capacitance. While some capacitance exists between any two electrical conductors in proximity in a circuit, a capacitor is a component designed to add capacitance to a circuit. The capacitor was originally known as a condenser or condensator. The original name is still widely used in many languages, but not in English.
⇒ The capacitance is measured in units of Farad (F).
The capacitance (C) of the capacitor is equal to the electric charge (Q) divided by the voltage (V):
⇒ C is the capacitance in farad (F)
⇒ Q is the electric charge in coulombs (C), that is stored on the capacitor
⇒ V is the voltage between the capacitor's plates in volts (V)
Capacitors in Parallel
Capacitors in a parallel configuration each have the same applied voltage. Their capacitances add up. Charge is apportioned among them by size. Using the schematic diagram to visualize parallel plates, it is apparent that each capacitor contributes to the total surface area.
Capacitors in Series
Connected in series, the schematic diagram reveals that the separation distance, not the plate area, adds up. The capacitors each store instantaneous charge build-up equal to that of every other capacitor in the series. The total voltage difference from end to end is apportioned to each capacitor according to the inverse of its capacitance. The entire series acts as a capacitor smaller than any of its components.