The Inductance reference article from the English Wikipedia on 24-Jul-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Inductance

Inductance is a physical characteristic of an inductor, which produces a voltage proportional to the instantaneous change in current flowing through it.

The inductance of a solenoid (an idealization of a coil) is defined as:

μ is the permeability of the core, N is the number of turns, A is the cross sectional area of the coil, and l is the length.

This, and the inductance of more complicated shapes, can be derived from Maxwell's equations.

The voltage generated is as follows:

,

where V is the voltage generated, di/dt is the rate of change of current, and L is a property of the device called inductance. The SI unit of inductance is the henry (H).

The operation of an inductor can be understood using a simple loop of wire as an example. The current flowing through the loop of wire produces a magnetic field by Ampere's law. A change in current (di/dt) results in a change in this magnetic field. This changing magnetic field causes an electromotive force in the conductor under Faraday's law of induction, which results in a voltage (V) forming in a such a direction as to oppose the change in current (see Lenz's law). The constant of proportionality L, which tells us for a particular device how big a voltage should be expected for a given change in current, is called the inductance.

See also

Inductor, alternating current, electricity

This is the "Inductance" reference article from the English Wikipedia. All text is available under the terms of the GNU Free Documentation License. See also our Disclaimer.