IEVref: 131-12-43 ID: Language: en Status: Standard Term: impedance Synonym1: complex impedance [Preferred] Synonym2: Synonym3: Symbol: $\underset{_}{Z}$ Definition: for a passive linear two-terminal element or two-terminal circuit with terminals A and B under sinusoidal conditions, quotient of the phasor ${\underset{_}{U}}_{\mathrm{AB}}$ representing the voltage (131-11-56) between the terminals by the phasor $\underset{_}{I}$ representing the electric current in the element or circuit $\underset{_}{Z}=\frac{{\underset{_}{U}}_{\text{A}\text{B}}}{\underset{_}{I}}$ where the sinusoidal voltage ${u}_{\text{A}\text{B}}={v}_{\text{A}}-{v}_{\text{B}}$ represented by the phasor ${\underset{_}{U}}_{\mathrm{AB}}$ is the difference of the electric potentials ${v}_{\text{A}}$ at A and ${v}_{\text{B}}$ at B, and where the sinusoidal electric current represented by the phasor $\underset{_}{I}$ is taken positive if its direction is from A to B and negative if its direction is from B to ANote 1 to entry: The impedance of an element or circuit is the inverse of its admittance. It is equal to $\underset{_}{Z}=R+\mathrm{j}X=Z{\mathrm{e}}^{\mathrm{j}\phi }$, where R is resistance to alternating current, X is reactance, Z is apparent impedance, and φ is displacement angle. Note 2 to entry: With a suitable qualifier, the word impedance is used to form composite terms designating quantities of the same kind as impedance, e.g.: transfer impedance, characteristic impedance. Note 3 to entry: The coherent SI unit of impedance is ohm, Ω. Publication date: 2013-08 Source: Replaces: Internal notes: 2017-06-02: Cleanup - Remove Attached Image 131-12-431.gif CO remarks: TC/SC remarks: VT remarks: Domain1: Domain2: Domain3: Domain4: Domain5: