Reactance is the opposition to a change in current or voltage in a circuit. A magnetic field produced in the circuit resists the change of current and electric field resists the change of voltage in the circuit.

When an alternating current flow in a circuit, a magnetic field is produced which opposes the change of current, this is called inductive reactance & when electric field opposes the change of voltage, this is called capacitive reactance. The reactance is denoted by X, its XL for Inductive reactance & Xc for capacitive reactance.

(Note: – Reactance is possible only in ac circuit & not in DC circuit as voltage & current is constant in DC circuit. In DC circuit, only resistance behavior is experienced in the circuit. )

The value of Inductive Reactance –   XL = jωL   =  2πfL

The value of Capacitive Reactance –   XC = 1/jωC  =  1/2πfC

where  jω =  2πf  (f = frequency ), L = Inductance, C= Capacitance