Inductor A coil of wire wound according to various designs, with or without a core of ferromagnetic material, to concentrate the magnetic flux resulting from current flowing in the wire. The coiling of the wire and/or the addition of a ferromagnetic
core increases the self-inductance compared with that of a straight wire having the same length. Also see INDUCTANCE; INDUCTION, 1; and SELF-INDUCTANCE, 1.
inductor alternator See ALTERNATOR.
inductor amplifier See MAGNETIC AMPLIFIER.
inductor decade See DECADE INDUCTOR.
inductor microphone See INDUCTIVE MICROPHONE.
inductors in parallel See PARALLEL INDUCTORS.
inductors in parallel-series See PARALLELSERIES
INDUCTORS.
inductors in series See SERIES INDUCTORS.
inductors in series-parallel See SERIES-PARALLEL
INDUCTORS.
inductor substitution box An enclosed assortment of common-value inductors that can be switched, one at a time, to a pair of terminals. In troubleshooting and circuit development, any of several useful fixed inductances can be thus obtained.
inductance Symbol, L. Unit, henry. In a conductor,device, or circuit, the inertial property (caused by an induced reverse voltage) that opposes the flow of current when a voltage is applied;
it opposes a change in current that has been established. Also see HENRY, INDUCTION, and MUTUAL INDUCTANCE.
inductance bridge An alternating-current bridge for measuring inductance in terms of a standard inductance or a standard capacitance. See, for example, HAY BRIDGE, MAXWELL BRIDGE, and OWEN BRIDGE.
inductance-capacitance Abbreviation, LC. 1. A combination of inductance and capacitance in a circuit, such as a filter, a parallel-resonant circuit, or a series-resonant circuit. 2. Pertaining to a device for measuring inductance and capacitance (e.g., LC bridge and LC meter).
inductance-capacitance bridge An alternatingcurrent bridge for measuring inductance and capacitance only.
inductance-capacitance filter A filter composed of inductors and capacitors. Also called LC filter.
inductance-capacitance meter A direct-reading meter for measuring inductance and capacitance.
inductance-capacitance-resistance Abbreviation,LCR.
1. A combination of inductance, capacitance,and resistance in a circuit, such as a basic tuned circuit. The resistive component represents loss in the inductor and capacitor.
2. Pertaining to a device for measuring inductance, capacitance,
1. A combination of inductance, capacitance,and resistance in a circuit, such as a basic tuned circuit. The resistive component represents loss in the inductor and capacitor.
2. Pertaining to a device for measuring inductance, capacitance,
and resistance (e.g., LCR bridge and LCR meter).
inductance-capacitance-resistance bridge See IMPEDANCE BRIDGE.
inductance coil See INDUCTOR.
inductance filter A filter using only an inductor,usually a coil of wire.
inductance-resistance time constant The time constant t (see ELECTRICAL TIME CONSTANT) of a circuit containing, ideally, only inductance and resistance. Mathematically, t = LR, where t is in seconds, L is the inductance in henrys, and R is the resistance in ohms. Also called LR time constant.
inductance standard A highly accurate, stable inductor
used in precision measurements. Also see
PRIMARY STANDARD and SECONDARY STANDARD.
induction
1. The ability of an alternating, pulsating,
or otherwise changing current flowing in one
circuit to set up a current in a nearby circuit. The
circuits need not be physically connected, but
need only be linked by magnetic lines of flux. Also
see SELF-INDUCTION.
2. The phenomenon
whereby a body becomes electrically charged by
the field surrounding a nearby charged body.
Also see ELECTRIC CHARGE.
induction coil A special high-voltage step-up transformer having an open core and a vibratorinterrupter in series with the primary winding,which carries direct current from a battery. The current is broken up into short pulses by the interrupter,and a high alternating-current voltage is generated in the secondary winding.
induction compass A compass whose indications depend on current induced in a coil revolving in the earth’s magnetic field. Compare GYROCOMPASS and MAGNETIC COMPASS.
induction factor The ratio of total current to nonproductive
current in an alternating-current circuit.
induction field The portion of an electromagnetic field that returns to a radiator, such as a coil, as opposed to the RADIATION FIELD.
induction frequency converter A mechanical device used for converting a signal at a fixed frequency to a signal at another fixed frequency.
induction furnace A furnace in which highfrequency magnetic fields induce currents in metal ores, causing the ore to become hot enough to melt.
induction heater A high-power, radio-frequency generator designed especially for induction heating.
induction heating The heating of metallic work samples by placing them in (but insulated from) a WORK COIL carrying current from a high-power radio-frequency generator. The workpiece is heated
by radio-frequency currents induced in it as a result of the intense alternating magnetic field within the coil. Compare DIELECTRIC HEATING.
induction loss Loss of energy from a currentcarrying conductor because of inductive coupling to a nearby conductor.
induction modulator See ELECTROMECHANICAL
MODULATOR.
induction motor An electric motor in which the stator’s rotating magnetic field makes the rotor revolve.
induction speaker An acoustic loudspeaker in which an audio-frequency current is passed through a diaphragm or coil located in a constant magnetic field. This results in movement of the diaphragm or coil.
induction transducer See INDUCTIVE TRANSDUCER.
induction-type landing system See DINGLEY INDUCTION-TYPE LANDING SYSTEM.
induction welding Welding in which the heating current flowing in the workpieces is induced by an electromagnetic field.
inductive capacitor A wound capacitor in which
the inductance of the roll is controlled and specified.
Such a capacitor is useful in compact filters
and in single-frequency bypassing, where the reactive
components are supplied by the capacitor.
Compare NONINDUCTIVE CAPACITOR.
inductive circuit
1. A circuit in which inductance predominates.
2. A (theoretical) circuit containing inductance only.
inductive coupling The transfer of energy between two inductors (or inductive devices) by a linking electromagnetic field. Also see COEFFICIENT OF COUPLING, COUPLING, INDUCTION, and MUTUAL INDUCTANCE.
inductive feedback See MAGNETIC FEEDBACK.
inductive heater See INDUCTION HEATER.
inductive heating See INDUCTION HEATING.
inductive kick See BACK VOLTAGE and KICKBACK.
inductive load A load device that approaches a pure inductive reactance (e.g., loudspeaker and electric motor).
inductive loading In an antenna, the addition of
inductance in series with the element(s). This reduces
a given physical length. It can also serve to
reduce the physical length required for a radiator having a specified resonant frequency. Compare CAPACITIVE LOADING.
inductive logic A form of reasoning that demonstrates that a certain conclusion is highly probable, given a certain set of circumstances. This is of interest to researchers in artificial intelligence (AI). Compare DEDUCTIVE LOGIC.
inductive microphone A microphone in which sound waves vibrate a conductor or coil in a strong magnetic field, producing a corresponding alternating-current output by the resulting induction.
Example: dynamic microphone.
induction neutralization Neutralization of a vacuum-tube radio-frequency power amplifier, via negative feedback from the output to the input through coupling coils.
inductive reactance Symbol, XL. Unit, ohm. The reactance exhibited by an ideal inductor, considered as a positive imaginary-number quantity; XL= j6.28fL, where XL is in ohms, f is the frequency in Hertz, L is the inductance in henrys, and j is the unit imaginary number (the square root of –1). Alternatively, f can be specified in megahertz,and L in microhenries. In a pure inductive reactance,current lags 90 degrees behind voltage.Also see INDUCTANCE, INDUCTION, INDUCTOR,and REACTANCE.
inductive switching Switching operations in a circuit containing an inductor. Switching time is influenced by the INDUCTANCE-RESISTANCE TIME CONSTANT of the inductor; overall operation is affected by the back voltage generated by the inductor.
inductive transducer A transducer in which the
sensed phenomenon causes a change in inductance (or reluctance), which, in turn, causes a proportional change in output current, voltage,frequency, or bridge balance.
Compare CAPACITIVE TRANSDUCER, CRYSTAL TRANSDUCER,MAGNETIC TRANSDUCER, and RESISTIVE
Compare CAPACITIVE TRANSDUCER, CRYSTAL TRANSDUCER,MAGNETIC TRANSDUCER, and RESISTIVE
TRANSDUCER.
inductive trimmer See TRIMMER INDUCTOR.
inductive tuning Also called permeability tuning. In a radio receiver, transmitter or transceiver, the adjustment of frequency by changing the inductance of a coil having a movable core.
inductivity See DIELECTRIC CONSTANT.
inductometer An instrument for measuring inductance in terms of the resonant frequency of an INDUCTANCE-CAPACITANCE (LC) circuit, in which L is the unknown inductance and C is calibration capacitance.