inductor

inductor, electric device consisting of one or more turns of wire and typically having two terminals. An inductor is usually connected into a circuit in order to raise the inductance to a desired value. Since inductance is a property that varies with frequency, inductors range from a single loop in a length of wire (used at ultrahigh frequencies), through spirals in the copper coating of an etched circuit board (used at very high frequencies), to large coils of insulated wire wound onto iron or ferrite cores. For radio use, inductors often have air cores to avoid the losses caused by magnetic hysteresis and by eddy currents that occur when solid cores are used. Solid cores, however, offer the advantage of raising the inductance that can be obtained from a coil of a given number of turns of wire. Ferrites are often used, since they are nonconductors and are immune to eddy currents.

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inductor

A coil of wire that generates a magnetic field when current is passed through it. The strength of the magnetic field is measured in henrys (H). When the current is removed, as the magnetic field disintegrates, it "induces" a brief current in the opposite direction of the original. Thus "induction" is caused by the opening and closing of a DC circuit or the continuous changing of directions in an AC circuit.

High-Frequency Filters
An induction coil impedes the flow of high-frequencies in an AC circuit, which is why inductors are used as surge protectors, choking off any high-frequency shifts. The tiny donuts placed on the end of signal cables and the load coils placed into telephone networks are examples. See induction.

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inductor

a component, such as a coil, in an electrical circuit the main function of which is to produce inductance

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Inductor

A device for introducing inductance into a circuit. The term covers devices with a wide range of uses, sizes, and types, including components for electric-wave filters, tuned circuits, electrical measuring circuits, and energy storage devices.

Inductors are classified as fixed, adjustable, and variable. All are made either with or without magnetic cores. Inductors without magnetic cores are called air-core coils, although the actual core material may be a ceramic, a plastic, or some other nonmagnetic material. Inductors with magnetic cores are called iron-core coils. A wide variety of magnetic materials are used, and some of these contain very little iron.

In fixed inductors coils are wound so that the turns remain fixed in position with respect to each other. Adjustable inductors have either taps for changing the number of turns desired, or consist of several fixed inductors which may be switched into various series or parallel combinations. Variable inductors are constructed so that the effective inductance can be changed. Means for doing this include (1) changing the permeability of a magnetic core; (2) moving the magnetic core, or part of it, with respect to the coil or the remainder of the core; and (3) moving one or more coils of the inductor with respect to one or more of the other coils, thereby changing mutual inductance. See Inductance

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Inductor

A device for introducing inductance into a circuit. The term covers devices with a wide range of uses, sizes, and types, including components for electric-wave filters, tuned circuits, electrical measuring circuits, and energy storage devices.

Inductors are classified as fixed, adjustable, and variable. All are made either with or without magnetic cores. Inductors without magnetic cores are called air-core coils, although the actual core material may be a ceramic, a plastic, or some other nonmagnetic material. Inductors with magnetic cores are called iron-core coils. A wide variety of magnetic materials are used, and some of these contain very little iron.

In fixed inductors coils are wound so that the turns remain fixed in position with respect to each other. Adjustable inductors have either taps for changing the number of turns desired, or consist of several fixed inductors which may be switched into various series or parallel combinations. Variable inductors are constructed so that the effective inductance can be changed. Means for doing this include (1) changing the permeability of a magnetic core; (2) moving the magnetic core, or part of it, with respect to the coil or the remainder of the core; and (3) moving one or more coils of the inductor with respect to one or more of the other coils, thereby changing mutual inductance.