# impedance

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## im·ped·ance

(ĭm-pēd′ns)
n.
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.

## impedance

(ɪmˈpiːdəns)
n
1. (Electronics) a measure of the opposition to the flow of an alternating current equal to the square root of the sum of the squares of the resistance and the reactance, expressed in ohms. Symbol: Z
2. (Electronics) a component that offers impedance
3. (General Physics) Also called: acoustic impedance the ratio of the sound pressure in a medium to the rate of alternating flow of the medium through a specified surface due to the sound wave. Symbol: Za
4. (General Physics) Also called: mechanical impedance the ratio of the mechanical force, acting in the direction of motion, to the velocity of the resulting vibration. Symbol: Zm

## im•ped•ance

(ɪmˈpid ns)

n.
1. the total opposition to alternating current by an electric circuit, equal to the square root of the sum of the squares of the resistance and reactance of the circuit and usu. expressed in ohms.
2. the ratio of the force on a system undergoing harmonic motion to the velocity of the particles in the system.
[1886]

## im·ped·ance

(ĭm-pēd′ns)
A measure of the opposition to the flow of an electric current through a circuit of alternating current. Impedance is measured in ohms.
ThesaurusAntonymsRelated WordsSynonymsLegend:
 Noun 1 impedance - a material's opposition to the flow of electric current; measured in ohmselectrical phenomenon - a physical phenomenon involving electricityohmage - the ohmic resistance of a conductor
Translations
impedanssi
impedancija
impedancia

## impedance

[ɪmˈpiːdəns] N (Elec) →
References in periodicals archive ?
Alternatively, thoracic impedance has been used as a noninvasive means to assess hemodynamics during exercise.
Eluna devices include wandless radio frequency telemetry for efficient device programming and interrogation at implant, the most physiologic therapy available via Closed Loop Stimulation, and HF Monitor and thoracic impedance diagnostics to provide vital information on heart failure progression.
The use of EIT/ERT for medical applications goes back to the work on thoracic impedance measurements and impedance pneumography during the 1950s and 1960s [23].
The Heart Failure Monitor has a number of settings, including a thoracic impedance feature that predicts imminent cardiac decompensation, heart failure and helps physicians to prevent hospitalization.
They sense minute ventilation by emitting a pulsed current and detecting the changes in thoracic impedance during the respiratory cycle.

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