# Capacitive & Inductive Reactance

Reactance has some similarities with resistance and can be thought of in basic terms as resistance to alternating currents. This includes currents at radio frequencies.

### Capacitive Reactance

The impedance of a capacitor is given by the formula

$Z = {1 \over j\omega C}$

Where $C$ is the capacitance, $\omega$ is $2 \pi f$, and $f$ is the frequency. $j$ is “operator j” from phasor analysis.

In prasctical terms this leads to:

$X_c = \frac {1} {2\pi F C}$ where

• $X_c$ is capacitive reactacnce
• F is the frequency of operation in Hertz
• C id the capacitance in Farads

### Inductive Reactance

The impedance of an inductor is given by the formula

$Z = j \omega L \,$

where $Z\,$ is the impedance, $\omega\,$ is $2 \pi f\,$, and $f\,$ is the frequency. $j\,$ is “operator j” from phasor analysis.

In pracical terms this leads to:

$X_c = 2 \pi F L$ where:

• $X_c$ is capacitive reactance
• F is the frequency of operation in Hertz
• L is the inductance in Henries