Dictionary:

impedance

  (ĭm-pēd'ns)

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.

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