# Inductor Impedance

The inductor is a reactive component and its impedance is a complex number. Ideal inductor impedance is purely reactive impedance. The impedance of an inductor increase with frequency as shown below by the impedance formula for an inductor. At low frequencies, the impedance of the inductor is low and its acts similar to a close circuit. At low freqencies, current will flow through the inductor. At high frequencies, the impedance of the inductor is high and its acts similar to an open circuit. $Z_L (\Omega )=\mathrm{j}\omega L$ $\omega =2\pi f$

where :

f is the frequency in Hertz, (Hz)

L is the inductance in Henry, (H)

The j indicates the phase. The voltage across an inductor leads the current by 90°. Figure 1 shows a visual representation of an AC voltage and current at the terminals of an inductor:

In figure 2, we have a Cartesian representation of impedance. In Cartesian form, the impedance is defined as: $Z (\Omega )= R + \mathrm{j}X$

The real part (x-axis) of impedance is the resistance (R) and the imaginary part (y-axis) is the reactance (X). $R (\Omega )= 0$ $X (\Omega )=\omega L=2\pi f L$ Figure 3 : Real model of an inductor $C = Inter-Winding\ Capacitance\\ R_{ac} = AC\ Resistance\\ R_{dc} = DC\ Resistance\\ L = Ideal\ Inductor\\$