# reactance

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## reactance:

see impedanceimpedance,
in electricity, measure in ohms of the degree to which an electric circuit resists the flow of electric current when a voltage is impressed across its terminals.
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## Reactance

The imaginary part of the impedance of an alternating-current circuit.

The impedance Z of an alternating current circuit is a complex number given by Eq. (1).

(1) (2) (3) The imaginary part X is the reactance. The units of reactance, like those of impedance, are ohms. Reactance may be positive or negative. For example, the impedance of an inductor L at frequency &ohgr; is given by Eq. (2), so X is positive. The impedance of a capacitor C is given by Eq. (3), so X is negative.

The reactance of a circuit may depend on both the resistors and the inductors or capacitors in the circuit. For example, the circuit in the illustration has admittance [Eq. (4)] and impedance [Eq. (5)], so that the reactance [Eq. (6)], depends on both the capacitor C and the resistor R. (4) (5) (6) See Admittance, Electrical impedance

## Reactance

in electricity, a quantity characterizing the opposition presented to an alternating current by the capacitance and inductance of a circuit or part of a circuit. Reactance is measured in ohms.

In the case of a sinusoidal current in a circuit where inductive and capacitive circuit elements are connected in series, the reactance x can be expressed as the difference between the inductive and capacitive reactances: Here, to is the angular frequency of the current, L is the inductance of the circuit, and C is the capacitance of the circuit. Reactance is equal to the ratio of the amplitude of the voltage on the terminals of a circuit having little resistance and the amplitude of the current through the circuit. When an alternating current flows in a circuit having only reactance, energy is transferred from the current source to the electric or magnetic field produced, respectively, by the capacitive or inductive circuit element and then back to the current source; the average power during a period is equal to zero. The presence of reactance in a circuit causes a phase difference between the voltage and the current.

When the current in a circuit is nonsinusoidal, the reactance is different for the individual harmonic components of the current.

## reactance

[rē′ak·təns]
(electricity)
The imaginary part of the impedance of an alternating-current circuit.

## reactance

1. the opposition to the flow of alternating current by the capacitance or inductance of an electrical circuit; the imaginary part of the impedance Z, Z = R + iX, where R is the resistance, i = &#221A--1, and X is the reactance. It is expressed in ohms
2. the opposition to the flow of an acoustic or mechanical vibration, usually due to inertia or stiffness. It is the magnitude of the imaginary part of the acoustic or mechanical impedance
References in periodicals archive ?
The finding involving participation in decision-making having a significantly positive relationship with workplace deviance was not expected as reactance theory anticipated a negative relationship.
XrsSD: average reactance with standard deviation; RrsSD: average resistance with standard deviation; 'significant differences (ANOVA test) for p < 0.05; AK: patients with controlled asthma; ANK: patients with uncontrolled asthma; K: control group.
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Thus, we conclude that the resistance and reactance parameters of IOS may be useful in clinical settings.
Estimated Equivalent Circuit Parameters Parameter Value, ohm Stator winding resistance [R.sub.1] 0.276 Stator leakage reactance [X.sub.1] 1.56 Magnetizing reactance [X.sub.m] 21.9 Core loss resistance [R.sub.c] 722 Rotor winding resistance [R.sub.2] 0.207 Rotor leakage reactance 1.05
Such assessment provides possibility in each case to take into account (or ignore) the mass reactance forces effect onto fluctuations in the fluid of the given material object.
Convergent validity was examined by calculating the correlation between the GSE with health locus of control, psychological reactance, and attitude towards drug treatment.
This may even lead to a psychological reactance response--a negative reaction toward persuasion attempts (Brehm and Brehm 1981).
Psychological reactance (PR) is the reaction (of irritation or disgust) that appears as a response to the perception of loss of freedom, and depends on the importance of the behaviour threatened and on age (Brehm, 1989; Brehm & Brehm, 1981).

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