impedance

1. (Symbol Z) A measure of the total opposition to current flow in an alternating current circuit, made up of two components, ohmic resistance and reactance, and usually represented in complex notation as Z = R + iX, where R is the ohmic resistance and X is the reactance.
2. An analogous measure of resistance to an alternating effect, as the resistance to vibration of the medium in sound transmission.

A measure of the apparent resistance posed by an electrical circuit to an alternating current (AC).

• The term impedance is most often encountered in dealing with antennas and speakers in television, stereo, and radio systems.

(1) The opposition to the flow of alternating current in a circuit. Represented by the letter "Z" and measured in ohms, impedance is the combination of resistance, inductance and capacitance of the circuit. See ohm.

(2) The opposition that a speaker produces to the alternating current coming from an amplifier. The lower the impedance, the more power required. Most speakers have an impedance of four to eight ohms. See ohm.

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In alternating-current electric circuits, a quantitative measure of the opposition to the flow of current upon the application of voltage; measured in ohms.

Obstruction or opposition to passage or flow, as of an electric current or other form of energy.

• acoustic i. — an expression of the opposition to passage of sound waves, being the product of the density of a substance and the velocity of sound in it.

(Z) Measured in ohms it is the total opposition to the flow of current offered by a circuit. Impedance consists of the vector sum of resistance and reactance.

Common misspelling(s) of impedance

• impedence