Electric impedance

Electric impedance is the scalar value which is equal to the relation of effective or amplitude value of a sinusoidal voltage on the passive electric circuit or its element and accordingly the effective or amplitude value of a sinusoidal electric current in this circuit or in this element.

Electric impedance is measured in ohms (Ω) and determining by the formula:

$z_{e}={\frac {U}{I_{e}}}={\frac {U_{m}}{I_{em}}}$

The full electric impedance is equal to

$z_{e}={\sqrt {r_{e}^{2}+x_{e}^{2}}}$ , $\phi =\arctan {\frac {x_{e}}{r_{e}}}$

where

$r_{e}=z_{e}\cos \phi$ is the real part of the complex electric impedance, named the effective electric impedance;

$x_{e}=z_{e}\sin \phi$ is the imaginary part of the complex electric impedance, named the reactive electric impedance.

References

[1] Pohl R. W., Electrizitâtslehre, Berlin-Gottingen-Heidelberg: Springer-Verlag, 1960.

[2] Popov V. P., The Principles of Theory of Circuits, – M.: Higher School, 1985, 496 p. (In Russian).

[3] Küpfmüller K., Einführung in die theoretische Elektrotechnik, Springer-Verlag, 1959.