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