What Is A Capacitor & What Are The Various Types of Capacitors
Last Updated on October 12, 2015 by Sasmita
What Is A Capacitor
Capacitors are simple passive devices which are used to store electricity. The capacitor has the ability or “capacity” to store energy in the form of an electrical charge producing a potential difference (Static Voltage) across its plates, much like a small rechargeable battery.
Capacitor Symbol
A capacitor is formed from two conducting plates separated by air or by some form of a good insulating material such as waxed paper, mica, ceramic, plastic or some form of a liquid gel. The insulating layer between a capacitors plates is commonly called the Dielectric.
Due to this insulating layer, the d.c. current can not flow through the capacitor but instead a voltage is produced across the plates in the form of an electrical charge.
If a current i flows, positive change, q, will accumulate on the upper plate. To preserve charge neutrality, a balancing negative charge will be present on the lower plate.
Hence, there will be a potential energy difference (or voltage v) between the plates which is proportional to the charge q.
where A is the area of the plates
d is their separation
Ɛ0 is the permittivity of the insulating layer ( Ɛ0 = 8.85 pF/m for vacuum).
The capacitance is given by the following expression :
The capacitance is measured in Farads (F)