Reactance is similar to resistance but it applies to AC circuits. Reactance usually changes if the frequency changes.

• Reactance is measured in Ohms
• Reactance applies to capacitors
• Reactance applies to inductors
• Reactance is the same as impedance for a purely capacitative circuit
• Reactance is the same as impedance for a purely inductive circuit
• Reactance is a measure of the oposition to current flow due to the capacitor or inductor

Capacitative Reactance X_c

X_c = 1 / 2 π f C

Inductive Reactance X_L

X_L = 2 π f L

• f is the frequency of the AC signal in Hertz
• C is the capacitance in Farads
• L is the inductance in Henries
• π is Pi = 3.141 approx