Concept and Definition of Capacitor

Concept and Definition of Capacitor

Capacitor is an electronic component which is store the charge.

All capacitors consist of two parallel conducting plates separated by an insulating material called dielectric. Leads, for connection are brought out from the two conducting plates.

Construction of a basic capacitor

Types and symbol

Fixed capacitors

The capacitance of a fixed capacitor remains constant.

Fixed Capacitor

Variable capacitors

The variable capacitor will be adjustable.

Variable Capacitor

Capacitor and Capacitance

A capacitor is formed if two conducting surface are separated by insulating medium
called dielectric.
Material used as a dielectric medium are mica, glass, paraffin paper, polystyrene, oil, air etc.

Capacitance is defined as the property of a capacitor store electric energy in form of static charge

Construction of a capacitor

Capacitor with air acting as dielectric

Relation between charge and applied voltage

The charge on capacitor is proportional to the externally applied voltage across it

Q ∝ V ____________________ (1)

or Q = CV ________________(2)

Where C is capacitance

Capacitance C = Q/V______(3)

Capacitors in Series

Consider three capacitors C1, C2, C3.

Dc voltage applied across the series combination through switch. The switch is closed all the capacitors will get charged.

The displacement of electrons are same

Let the charge acquired by each capacitor be Q Coulombs.

Three Capacitors in Series

Equivalent capacitance

Potential difference on three capacitors will be V1, V2 and V3 assuming capacitors fully charged

relation between voltage, charge and capacitance of individual capacitor

V1 = Q1/C1, V2 = Q/C2, V3 = Q/C3 _____________(1)

Source voltage V = V1+V2+V3

V = Q1/C1+Q/C2+Q/C3

V = Q [1/C1+1/C2+1/C3]

V = Q/Cs

Equivalent capacitance 1/Cs = 1/C1+1/C2+1/C3

1/Cs = 1/C1+1/C2+1/C3--------+1/Cn

Capacitors in Parallel

Three capacitors connected parallel in across a dc supply of V volts.

The capacitance of three capacitors are C1, C2, and C3 respectively and switch SW is used to connect or disconnect the source.

Parallel connection all the capacitors are charged to the same potential V.

Let the three capacitors be Q1, Q2 and Q3 respectively.

Q1 = C1V, Q2= C2V and Q3 = C3V

Equivalent to capacitance Cp

Q = CpV

Q = Q1+Q2+Q3

CpV = C1V + C2V + C3V

Cp = C1+C2+C3

Cp = C1+C2+C3---------+Cn

FAQ

What is capacitor

Capacitor is an electronic component which is store the charge.

All capacitors consist of two parallel conducting plates separated by an insulating material called dielectric. Leads, for connection are brought out from the two conducting plates.

Energy Stored by a Capactior

During the charging process of a capacitor transfer of charge takes place from one plate to its other plate. This charge always takes place against the opposition presented by the potential difference that exists between the plates.

The external charging source delivers (spends) energy which is stored by the capacitor in the form of electrostatic field set in the dielectric medium.

All capacitors consist of two parallel conducting plates separated by an insulating material called dielectric. Leads, for connection are brought out from the two conducting plates.

During the charging process of a capacitor transfer of charge takes place from one plate to its other plate. This charge always takes place against the opposition presented by the potential difference that exists between the plates.

The external charging source delivers (spends) energy which is stored by the capacitor in the form of electrostatic field set in the dielectric medium.