The above equation gives you the reactance of a capacitor. To convert this to the impedance of a capacitor, simply use the formula Z = -jX. Reactance is a more straightforward value; it tells you how much resistance a capacitor will have at a certain frequency. Impedance, however, is needed for comprehensive AC circuit analysis.
Functionally, a capacitor affords temporary electrical energy storage in the form of an electric potential where the capacitor's current leads its voltage by 90°. The formula for capacitor impedance is as follows: XC is the capacitive reactance that characterizes how much resistance a capacitor will have at a particular frequency.
Although capacitance in an AC circuit is easily discernible, the parameter impedance in an AC circuit requires thorough circuit analysis. Keeping this in mind, obtaining a greater understanding of the relationship between capacitance and impedance is paramount.
We will study capacitors and inductors using differential equations and Fourier analysis and from these derive their impedance. Capacitors and inductors are used primarily in circuits involving time-dependent voltages and currents, such as AC circuits. Most electronic circuits involve time-dependent voltages and currents.
At different frequencies, inductor impedances increase while capacitor impedances decrease. At very high frequencies, inductors can be modeled by open circuits, while capacitors can be approximated by short circuits.
The impedance of a capacitor, Zcap, can be calculated using the equation Lbl = Zcap / (2 * π * f). The actual inductance (Lbl) can be determined from the rising part of the impedance curve.