<electronics> (Or "potential difference", "electro-motive
force" (EMF)) A quantity measured as a signed difference
between two points in an electrical circuit which, when
divided by the resistance in Ohms between those points,
gives the current flowing between those points in Amperes,
according to Ohm's Law. Voltage is expressed as a signed
number of Volts (V). The voltage gradient in Volts per metre
is proportional to the force on a charge.
Voltages are often given relative to "earth" or "ground" which
is taken to be at zero Volts. A circuit's earth may or may
not be electrically connected to the actual earth.
The voltage between two points is also given by the charge
present between those points in Coulombs divided by the
capacitance in Farads. The capacitance in turn depends on
the dielectric constant of the insulators present.
Yet another law gives the voltage across a piece of circuit as
its inductance in Henries multiplied by the rate of change
of current flow through it in Amperes per second.
A simple analogy likens voltage to the pressure of water in a
pipe. Current is likened to the amount of water (charge)
flowing per unit time.
(1995-12-04)
Nearby terms:
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