Inductive Reactance

Inductive reactance, abbreviated as \(X_l\), describes the opposition that an inductor presents to the flow of alternating current (AC).  In an AC circuit, the current is constantly changing direction, oscillating back and forth.  When the current through an inductor changes, it induces a voltage in the coil according to Faraday's law of electromagnetic induction.  This induced voltage acts in a way that opposes the change in current.  As a result, inductors have a property called inductive reactance.

The inductive reactance is directly proportional to both the frequency of the AC signal and the inductance of the coil.  As the frequency increases, the inductive reactance also increases.  Similarly, if the inductance of the coil is increased, the inductive reactance will increase.  Inductive reactance, like resistance, affects the magnitude of the current in an AC circuit.  However, unlike resistance, inductive reactance also depends on the frequency of the AC signal. It is important in the analysis and design of AC circuits, where inductors are commonly used.

 

Inductive Reactance formula
\( X_l \;=\; 2 \; \pi \; f \; L   \)     (Inductive Reactance) \( f \;=\;    X_l \;/\; 2 \; \pi \; L \) \( L \;=\;   X_l \;/\; 2 \; \pi \; f  \)
Symbol	English	Metric
\( X_l \) = inductive reactance	\(H\)	\(kg-m^2\;/\;s^2-A^2\)
\( \pi \) = Pi	\(dimensionless\)
\( f \) = frequency	\(Hz\)	\(s^{-1}\)
\( L \) = Inductance	\(H\)	\(kg-m^2\;/\;s^2-A^2\)