reactance n : opposition to the flow of electric current resulting from inductance and capacitance (rather than resistance)

English

Noun

reactance (symbol X)

1. In the context of "physics|electric": opposition to the change in flow of current in an alternating current circuit, due to inductance and capacitance; the imaginary part of the impedance

Translations

• German: Blindwiderstand , Reaktanz
• Japanese: (yūdōteikō)

This article is about electronics. For a discussion of "reactive" or "reactance" in chemistry, see reactivity.

For a discussion of the psychological concept of reactance, see reactance (psychology).

Reactance is the imaginary part of electrical impedance, a measure of opposition to a sinusoidal alternating current. Reactance arises from the presence of inductance and capacitance within a circuit, and is denoted by the symbol \scriptstyle. The SI unit of reactance is the ohm.

Both reactance \scriptstyle and resistance \scriptstyle are required to determine the impedance \scriptstyle; although in some circumstances the reactance may dominate the impedance; at least an approximate knowledge of the resistance is required to establish this.

\tilde = R + j\Chi

Both the magnitude \scriptstyle and the phase \scriptstyle of the impedance depend on both the resistance and the reactance.

|\tilde| = \sqrt = \sqrt

\theta = \arctan

The magnitude is the ratio of the voltage and current amplitudes, while the phase is the voltage–current phase difference.

• If \scriptstyle, the reactance is said to be inductive
• If \scriptstyle, then the impedance is purely resistive
• If \scriptstyle