A capacitor is a device that is capable of storing electrical energy (or electric charge). It is essentially consists of two conducting materials (say plates) separated by an insulating medium dielectric. The most commonly used dielectrics are air, mica, paper etc. A capacitor is generally named after the dielectric used (for example, air capacitor, mica capacitor, paper capacitor etc.  The conducting materials may be in the form of either circular (or rectangular) plates or be of cylindrical (or spherical) shape. 

How does a Capacitor Store Charge?

A Capacitor stores charge when it is connected to D.C. supply. One plate A is joined to the positive end of the supply and the other plate B to the negative end. There is a momentary flow of electrons from A to B. As negatively-charged electrons are withdrawn from A, it becomes positive and these electrons collect on B, it becomes negative. Hence, a potential difference is establish between plates A and B. The transient flow of electrons gives rise to charging current.

capacitor and types of capacitorsThe process of electrons flow continuous till potential difference across capacitor plates becomes equal to battery voltage. When the capacitor is charged to the battery voltage V, the current flows stop.

Rating of Capacitors

Capacitors are rated in Farad

Types of Capacitors

Some Types of capacitors are explained in this article. These are given below:

Paper Capacitors

Paper capacitors are most common of all capacitors. For the construction of these capacitors two metal foils are separated by paper impregnated with a dielectric material such as wax, plastic or oil are rolled into compact cylinder. Connecting leads are attached to the metal plates.

 paper capacitorsCharacteristics of paper capacitors

Range :- 0.0001 μF to 2 μF

Working Voltage : – upto 2000 volts D.C.

Mica Capacitors

These capacitors consist of alternate thin sheets of metal foils separated by mica thin sheets. Alternate metal sheets are connected together and brought out as one terminal for one set of plates, while the opposite terminal connects to the other set of plates. The whole construction is encased in a plastic housing or moulded in Bakelite case.

types of capacitors mica capacitorsCharacteristics of mica capacitors

Range :- 2.5 pF to 0.05 μF

Working Voltage: – 500 to 2500 volts

Ceramic Capacitors

The ceramic is a dielectric material made from earth fired under extreme heat. Titanium oxides are used to obtain very high value of dielectric of ceramic materials. The ceramic capacitors may be disc type or tubular type.

ceramic capacitors

Characteristics of ceramic capacitors

Range :- 2.5 pF to 0.22 μF

Working Voltage: – 500 to 2500 volts

Electrolytic Capacitors

An electrolytic capacitor contains two aluminium electrodes. Between the two electrodes , absorbent gauze soaks up electrolyte to provide the required electrolysis that produces an oxide film at the positive electrodes when d.c. voltage is applied. The oxides film acts as an insulator and forms a capacitance between positive aluminium electrodes and the electrolyte in the gauze separator the negative aluminium electrode simply provides a connection to electrolyte. These are two types wet type and dry type.

electrolyte capacitorsCharacteristics of electrolytic capacitors

Range :- 1 pF to 2000 μF

Working Voltage: – 500 to 2500 volts