# Illustration AC circuit with a capacitive reactance of the capacitor

A simple alternating current circuit. An AC voltage $$U_{\text C}(t)$$ (e.g. a sinusoidal voltage), is applied to a capacitor and causes an AC current $$I_{\text C}(t)$$.
The capacitor has a capacitive reactance $$X_{\text C}$$, which depends on the frequency $$f$$ of the AC voltage and the capacitance $$C$$ of the capacitor.
In the case of a DC voltage, the capacitive reactance $$X_{\text C}$$ is infinite.