A capacitor or condenser is a passive electronic component consisting of a pair of conductors separated by a dielectric. When a potential difference exists across the conductors, an electric field is present in the dielectric. This field stores energy and produces a mechanical force between the plates. The effect is greatest between wide, flat, parallel, narrowly separated conductors.An ideal capacitor is characterized by a single constant value, capacitance, which is measured in farads. This is the ratio of the electric charge on each conductor to the potential difference between them. In practice, the dielectric between the plates passes a small amount of leakage current. The conductors and leads introduce an equivalent series resistance and the dielectric has an electric field strength limit resulting in a breakdown voltage.Capacitors are widely used in electronic circuits to block the flow of direct current while allowing alternating current to pass, to filter out interference, to smooth the output of power supplies, and for many other purposes.
Capacitance: If we have 2 conductors and we place charge +Q on one
and Q on the other, a potential difference V develops, the conductor with positive charge being at a higher
potential. The capacitance of this system, consisting of the two conductors, is C = Q / V.
For a parallel plate capacitor, C = (epsilon_0) A / d, where A is
the area of one of the plates (the two plates have the same area A) and d is the separation between the
If a dielectric (an insulator) with dielectric constant K fills the
space between the plates of a parallel plate capacitor, then the capacitance becomes KC, where C is the
capacitance in the absence of the dielectric.
The energy stored in a capacitor is Q^2 / 2C, where Q is the charge
on one plate. It is also given by (1/2) C V^2, where V is the potential difference across the plates
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