# Capacitive Reactance

MathML formulaFormula ImageStraight text formula
$X c = 1 2πfC$ Xc = 1 / (2πfC)

Where:

Xc = capacitive reactance, Ohms

f = frequency, Hertz

C = capacitance, Farads

Reactance, XC =

## Capacitors - Complex Impedance

When working with circuits that contain combinations of ideal capacitances, inductances and resistance, it is more correct to deal with capacitance in terms of a "complex impedance". In this form, components have a combination of a "real" resistance part, and an "imaginary" reactance part. The pure capacitor, of course, has a zero real part (it doesn't have resistance) but a negative imaginary part.

MathML formulaFormula ImageStraight text formula
$X c = -j ωC = -j 2πfC$ Xc = -j / (ωC) = -j / (2πfC)

Where:

j = √-1

Xc = capacitive reactance, Ohms

ω = angular frequency, radians per second

f = frequency, Hertz

C = capacitance, Farads

Note that the above expression can also be modified by multiplying above and below by j to give:

MathML formulaFormula ImageStraight text formula
$X c = 1 jωC = 1 j2πfC$ Xc = 1 / (jωC) = 1 / (j2πfC)