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A Capacitor is a passive electronic component that stores energy in the form of an electrostatic field. Therefore Capacitors are used to store electric charge. The standard unit of capacitance is the farad, abbreviated F, and the symbol used to indicate a capacitor is -||-. In other words, capacitance is measured in units called Farad: F.
Structure and working
A capacitor consists of two plates of a conducting material separated by a space filled by an insulator. The insulating layer is called the Dielectric of the capacitor.
The fundamental property of a capacitor is that it can store charge. Hence, it could be used to store electric field energy. The capacitance C between two appropriate surfaces is defined by V=q\c where V is the potential difference between the surfaces and Q is the magnitude of the charge distributed on either surface. Capacitance is directly proportional to the surface areas of the plates, and is inversely proportional to the plates separation.
The capacitor also functions as a filter, passing alternating current (AC), and blocking direct current (DC).
Capacitance is measured in units called Farad: F
microfarad: µF (1 µF = 10-6 F)
nanofarad: nF (1 nF = 10-9 F)
picofarad: pF (1 pF = 10-12 F)
Time constant of capacitance
The time required for a capacitor to get charged is proportional to the capacitance value and the resistance value.
The time constant of a resistance - capacitance circuit is:
T = R X C
Where T = time in seconds
Where R = resistance in ohms
Where C = capacitance in farads
Capacitors in series and parallel
When Capacitors are connected in parallel say C1,C2,C3.
Add capacitor values together as C1 + C2 + C3 + ..... to get net capacitor value
When capacitors are connected in series.
The net value is calculated in following manner
1 / (1 / C1 + 1 / C2 + 1 / C3 + .....)
Applications
Since capacitors smooth, rectify unwanted ripples and signals & maintain the contents of memory, they can be used for many applications like integrated circuit (IC) chips, dynamic random access memory (DRAM) in conjunction with transistors. Besides, large capacitors find application in the power supplies of electronic equipment of all types, including computers and their peripherals.
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