Capacitance, ability of a circuit
system to store electricity.
The capacitance of a capacitor is measured in farads and is
determined by the formula C = q/V, where q is the charge (in
coulombs) on one of the conductors and V is the potential
difference (in volts) between the conductors.
The capacitance depends only on the thickness, area, and
composition of the capacitor's dielectric.
This is the phenomenon where after a
capacitor has been charged for some time, and then discharged, some
stored charge will migrate out of the dielectric over time, thus
changing the voltage value of the capacitor. This is extremely
important in sample and hold circuit applications. The typical
method of observing Dielectric Absorption is to charge up a cap to
some known DC voltage for a given time, then discharge the
capacitor through a 2 ohm resistor for one second, then watch the
voltage on a high-input-impedance voltmeter. The ratio of recovered
voltage (expressed in percent) is the usual term for Dielectric
The capacitance of a condenser is
measured in farads.
A condenser of 1 farad capacitance will exhibit a change in
potential difference of 1 volt between its plates when 1 coulomb of
electricity is transferred from one plate to the other.
The standard abbreviation for
capacitance is C and the symbol for farads is letter F.