CAPACITORS

What is a Capacitor?

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A Capacitor is an electrical component used to store the energy in the form of electric fields.  A Capacitor consists of two conductors which are separated by an insulating material called dielectric. 

Dielectric can be glass,plastic film, paper or any non conducting material. When there is a potential difference between the two plates of the conductor then a static electric field will be produced across the dielectric, causing the positive charge to collect on one plate and negative charge to collect on another plate. The energy is stored in the form of electric field.

The symbol of a capacitor is given by    

                                                                 

Capacitance

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Capacitance is the ratio of the electric charge on each conductor to the potential difference between them. Capacitance is measured in the unit of Farad(F) which is equal to 1 cu per volt.
C=Q/V
C →Capacitance of the capacitor(in Farad)
Q → Electric Charge (in cu)
V → Voltage between capacitor plates (in V)
The capacitance value depends up on the value of dielectric constant.
A capacitor blocks DC and allows AC current to pass through it. When an AC current is given to the capacitor starts charging exponentially and when an load is connected then the capacitor discharges.

Types of capacitors

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There are different types of capacitors. Capacitors can be fixed or variable . They are again divided into polarized and non polarized.
Based on the conduction capacitors are divided in to two types. They are
  1)Ceramic capacitors 2)Electrolytic capacitors

Electrolytic capacitor is a fixed capacitor consisting of two electrodes separated by an electrolyte. Electrolytic capacitors provide high capacitance in small volume and are used mostly in Power supply filter circuits at lower frequencies.  Electrolytic capacitors are polarized.
Ceramic capacitors are non polarized and these are purely depend on the dielectric constant of the bulk capacitor. Most of low value capacitors are non polarized. 

Based up on the construction these capacitors are classified in to three types . They are

1) Parallel Plate capacitor 

2) Co-axial capacitor
3) Spherical capacitor

Applications

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Capacitors are widely used in various applications of electronics .

1.They are used as the energy storage devices.

2. They are used in filter networks(High pass filter, Low pass filter).
3.They are used in signal processing.
4. Blocking, Coupling and Bypass capacitors are used in amplifiers.

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