reactance


Also found in: Dictionary, Thesaurus, Medical, Acronyms, Wikipedia.

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.
..... Click the link for more information.
.

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

Circuit with a resistor and capacitor in parallelenlarge picture
Circuit with a resistor and capacitor in parallel

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 ?
According to Dowd and Seibel (1990), this balance is central to the development of an optimal level of reactance and, subsequently, a flexible autonomy and healthy identity.
Second, it was assumed that entrepreneurs who had been running their enterprise for only a short time would experience intense loss of freedom and show higher reactance than those who had been running it for an extended period of time and who had experienced profits despite tax obligations and/or who had adapted to the tax system.
In the second step, treatment time was included, and in the third step, measures of psychological processes (locus of control, reactance and self-efficacy) were included as predictor variables, taking each gender separately.
Convergent validity was examined by calculating the correlation between the GSE with health locus of control, psychological reactance, and attitude towards drug treatment.
The second aim was to test whether the combination of high financial literacy and a disclosure statement could lead to a psychological reactance response to the insurance agent.
The psychological reactance of older adults to unconventional advertising will be less than that of young people, and as a consequence their behaviour towards the advertiser will also be less negative.
The impulse oscillometric method is a Forced Oscillation Technique (FOT) that is capable of measuring respiratory impedance in terms of the Resistance (R) and Reactance (X) of the lungs at frequencies between 5 Hz-25 Hz [10].
summation]x--is the total inrush inductive reactance of electric motor and feeding power supply and electric line.
LED International Holdings and its subsidiaries specialize in the provision of EMC contracts under which the Group installs energy saving products in its customers' premises, including lighting and reactance filtering equipment supplied by the group, and the subsequent savings made by the customers in their electricity charges are then shared between the group and the customers thereby enabling the group to generate recurring revenue rather than one-off sales revenue.
Combined with a non-inductive Ayrton-Perry winding, inductive reactance and signal loss are virtually eliminated.