Capacitor is a basic electrical component that stores charge.It is constructed of two parallel conductive plates separated by insulating material called dielectric.Connecting leads are attached to parallel plates.
Lets consider initially capacitor is in uncharged (Neutral) state.In neutral state both plates of a capacitor have an equal number of free electrons.Electrons are removed from plate A and equal number of electrons are deposited on plate B. Plate A becomes positive and Plate B becomes negative. During charging, no electrons flow through dielectric because its an insulator,The movement of electrons is ceased when voltage across the capacitor equals to source voltage. Now if capacitor is disconnected from source, it retains charge and still it has voltage across its terminals.Charged capacitor acts as a temporary battery.
Amount of charge stored is directly proportional to applied voltage.Capacitance is the measure of capacitors ability to store charge.
Unit of capacitance is Farad.
From equation
Farad
Q = C V
=> 1 C = 1 Q/1 V
One farad is the amount of capacitance, when one coulomb of charge is stored with one volt across the plates.
NOTE :
Plate Area》
Capacitance is directly proportional to plate area
Higher the plate area, means higher amount of charge can be stored.
Plate Separation》
Capacitance is inversely proportional to plate separation
Higher the plate separation, means less amount of charge can be stored.
Force of attraction.
Dielectric Material》
Material placed between plates of capacitor is called dielectric material.
Measure of material’s ability to establish an electric field is called dielectric constant/relative permittivity.
Dielectric constant
Capacitance is directly proportional dielectric constant.
Breakdown Voltage 》
Maximum voltage that can be applied to capacitor without risk of damage to capacitor.
It is also called breakdown or working voltage.
Breakdown voltage of a capacitor is determined by dielectric strength of dielectric material used.
