## The impedance of a capacitor

The impedance of a component is the resistance of that component for
AC voltages. The symbol for resistance is R; the symbol for impedance is
X. The impedance of a capacitor is not zero; it depends on the capacity
(size of the plates) and the frequency of the signal (number of polarity
changes (forth and back) per second). The impedance can be calculated
using the following equation.

f is the frequency in Hertz; C is
the capacitance in Farad

Example: We have a 1nF capacitor and connect it to a 50Hz AC voltage
source. Calculate the impedance of the capacitor.

X_{C} =
1/(2∙π∙50∙10^{-9}) = 3.18MΩ.