Capacitors are devices which store electric charge and consist of two metal plates separated by a dielectric material. The unit of capacitance is Farad, microfarad, nanofarads. Some of the applications of capacitors are smoothening power supplies, filtering, tuning, coupling circuits, stores energy & release when needed.
Types of Capacitors:
Capacitors are classified on the basis of dielectric material used, nature of value and polarization etc. Common classification is based on the dielectric material used.
(I) Paper Capacitors:
Capacitors make use of thin sheets of paper wound with thin aluminum foils. The paper sheets used are impregnated with oils or waxes to increase dielectric strength. The capacitor is encapsulated in
(II) Mica Capacitors:
Mica capacitors are made by directly metallising the thin sheets of mica with silver and stacking together several such sheets to make complete capacitor as shown in Fig. 6.60. The assembly is encapsulated in resin.
(III) Ceramic Capacitors:
These capacitors use Steatite or Barium Titanate as dielectric material. A thin foil of ceramic is metallized on both sides and leads are connected. The body is then given several coats of lacquer.
(IV) Foil Plastic Film Capacitors:
These capacitors are similar to paper capacitors except that these use plastic film as insulating materials. Foil plastic film capacitor.
(V) Electrolytic Capacitors:
High value capacitance is realized using electrolytes. They are made up of a metal foil with a surface which has anodic formation of metal oxide film. This anodized foil is kept in electrolytic solution.