Reactance is the part of a circuit's total impedance not due to pure resistance, arising from inductance and capacitance, measured in ohms and given the symbol X.
Reactance is the portion of a circuit's total impedance that is not due to pure resistance. It arises from the energy-storing effects of inductance and capacitance, which oppose changes in current and voltage in an alternating current circuit. Measured in ohms and represented by the symbol X, reactance is the imaginary part of the complex impedance, distinct from the resistive part.
Because reactance depends on frequency, its effect grows or shrinks as the frequency of a signal changes. Inductive reactance increases with frequency, while capacitive reactance decreases, and together with resistance they determine the overall impedance a circuit or cable presents to a signal. This frequency dependence is important in audio, video, and high-frequency systems.
In commercial and industrial systems, reactance contributes to the characteristic impedance of cable and the behavior of circuits at different frequencies. Understanding reactance supports the analysis of how cable and components respond across a range of signals.
Because reactance depends on frequency, with inductive reactance rising and capacitive reactance falling as frequency increases, it shapes how cable and circuits respond across a range of signals, contributing along with resistance to the impedance a path presents.
At Windy City Wire, an understanding of electrical fundamentals like reactance supports the selection of low-voltage cable engineered for clean signal performance. Recognizing how reactance contributes to impedance helps customers appreciate the characteristics that affect signal behavior in their applications.
Symbol X (reactance)