What is Capacitor How Capacitors Works Introduction of Capacitor Capacitor

What is Capacitor How Capacitors Works Introduction of Capacitor Capacitor

What is a Capacitor?

A capacitor (originally known as a condenser)
A capacitor is a passive two terminal component which stores electric charge. This component consists of two conductors which are separated by a dielectric medium. The potential difference when applied across the conductors polarizes the dipole ions to store the charge in the dielectric medium.
The conductors can be thin films, foils or sintered beads of metal or conductive electrolyte, etc. The nonconducting dielectric acts to increase the capacitors charge capacity. A dielectric can be glass, ceramic, plastic film, air, vacuum, paper, mica, oxide layer etc. Capacitors are widely used as parts of electrical circuits in many common electrical devices.

The Capacitance of a Capacitor

Capacitance is the electrical property of a capacitor and is the measure of a capacitors ability to store an electrical charge onto its two plates with the unit of capacitance being the Farad (abbreviated to F) named after the British physicist Michael Faraday.
Capacitance is defined as being that a capacitor has the capacitance of One Farad when a charge of One Coulomb is stored on the plates by a voltage of One volt. Capacitance, C is always positive and has no negative units. However, the Farad is a very large unit of measurement to use on its own so sub-multiples of the Farad are generally used such as micro-farads, nano-farads and pico-farads.

Standard Units of Capacitance

• Microfarad  (?F)   1?F = 1/1,000,000 = 0.000001 = 10^-6 F
• Nanofarad  (nF)   1nF = 1/1,000,000,000 = 0.000000001 = 10^-9 F
• Picofarad  (pF)   1pF = 1/1,000,000,000,000 = 0.000000000001 = 10^-12 F

Capacitors are widely used in a variety of applications of electronic circuits such as

�         store charges such as in a camera flash circuit

�         smoothing the output of power supply circuits

�         coupling of two stages of a circuit (coupling of an audio stage with a loud speaker)

�         filter networks,tone control of an audio system

�         delay applications

�         tuning radios to particular frequencies

�         phase alteration. 

There are different types of capacitors,

they can be fixed or variable. They are categorized into two groups, polarized or non-polarized and Variable.

Electrolytic Capacitors

Electrolytic capacitors are high voltage capacitors which produce high value of capacitance in a small component at the expenses of wide tolerance in the marked value and the necessity of connecting the capacitor so that one terminal is always positive. When very large capacitance values are required, electrolytic capacitors are generally used. Due to their large capacitance and small size, they are also used in DC power supply circuits to help reduce the ripple voltage or for coupling and decoupling applications. High-capacity electrolytic, also known as supercapacitors or ultracapacitors, have applications similar to those of rechargeable batteries.

Ceramic Capacitors

Ceramic or Disc Capacitors are manufactured by coating 2 sides of a small porcelain or ceramic disc with silver and are then stacked together to create a capacitor. They are generally small, cheap and useful for high frequency applications, although their capacitance varies strongly with voltage. Although small in physical size, they have high dielectric constant.
They are non-polarized devices and the exhibit large non-linear changes in capacitance against temperature.
Ceramic capacitors have multiple layers in order to ensure that sufficient levels of capacitance can be obtained with a single capacitor package. Although other styles are available, the 3 main types of ceramic capacitors include leaded disc ceramic capacitors, multilayer surface mount chip ceramic capacitors and specialist microwave bare leadless disc ceramic capacitors.

 

Film Capacitors

The most commonly available of all types of capacitors are the film capacitors which consist of a relatively large family of capacitors with the difference being in their dielectric properties.
They can come in an assortment of shapes and case styles including wrap & fill (oval & round), epoxy case (rectangular & round) and metal hermetically sealed (rectangular & round).

 

Tantalum Capacitors

Similar to electrolytic capacitors, tantalum capacitors are also polarized but uses tantalum within the construction of the capacitor in order to provide extremely high levels of capacitance for any given volume. They offer a form of capacitor that provides a very high capacity density.
They are available in both wet (foil) and dry (solid) electrolytic types.

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