# Know The Basic Device – Capacitor

Capacitors are an essential part of the electrical circuit. It is one of the chief components of passive components.  The capacitor is a type of device that allows the current to pass through it and dissipate heat. The capacitor is a two-terminal device that is capable of storing the electrical energy in the form of charges.

The capacitor is generally represented as

Where the first symbol represents the standard representation and the second is for a polarized capacitor.

A capacitor consists of 2 parallel conductive plates which are electrically separated by air or by good insulating material like plastic, mica, ceramic, or waxed paper. The insulating layer seen between the conducting plates of the capacitor is known as the Dielectric.

The potential difference is experienced by the capacitor connected to a battery or electric source. When the current passes, dielectric field is seen as a result the positive charges are accumulated on one plate and negative charges gets collected on the other plate of the capacitor. When the plates remain neutral and a potential difference is established between the two plates. Once the capacitor approaches its steady state an electrical current flows through the capacitor due to the insulating properties of the dielectric between the plates.

The flow of electrons on the plates is known as the Charging Current. This current flows until the voltage across both plates is equal to the applied voltage Vc. When the voltage is applied to the capacitor and when charges are measured, the capacitance value of the capacitor and is given as:

C = Q/V

The function of A Capacitor

The capacitor basic function is to store the electrical energy in the circuit and supply that energy when necessary. In simple words, we can say that capacitor charges and discharges the electric energy stored in it.

## To Find The Capacitance

Capacitance is described as the ratio of the electric charge on each conducting plate to the potential difference between them.

SI unit of capacitance = Farad

1 Farad = 1 coulomb of charge stored per plate of the capacitor on the application of the voltage of One Volt.

### Coulomb’s Law

Coulombs law defines the force between two charges. The electric force between charged bodies which are at rest is called electrostatic force or Coulomb force. Coulomb’s law is also known as Coulomb’s inverse-square law and was found by Charles-Augustin de Coulomb.

The Force between the charge q1 and q2 is given by

$F=k_{e}\frac{q_{1}q_{2}}{r^{2}}$

Where

ke = 9.0 x 209 N ,. m2 / C2