Reactance on the Electrical Contractor's Exam

Reactance is represented by the letter X and is expressed in terms of ohms.

Reactance is the "opposition" to alternating current in a circuit.

This opposition is caused by both inductance and capacitance, therefore there is inductive reactance, capacitive reactance and, of course, plain reactance.

Let's look at their formulas.

Inductive Reactance (X_L) = 2 π x Frequency (F) x Inductance (L)
X_L = 6.28 x F x L

Capacitive Reactance (X_c) = 1/2 π x Frequency (F) x Capacitance(C)
X_c = 1/6.28 x F x C

Reactance (X) = Capacitive Reactance (X_c) - Inductive Reactance (X_L)