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# impedance

[im-peed-ns]
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noun
1. Electricity. 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 usually expressed in ohms. Symbol: Z
2. Also called mechanical impedance. Physics. the ratio of the force on a system undergoing simple harmonic motion to the velocity of the particles in the system.
3. something that impedes; an obstacle or hindrance.

## Origin of .css-1fxfie5{font-size:22px;}@media (max-width:768px){.css-1fxfie5{font-size:18px;margin:0 10px 10px 0;word-break:break-all;word-wrap:break-word;-webkit-hyphens:auto;-moz-hyphens:auto;-ms-hyphens:auto;hyphens:auto;line-height:22px;}}impedance

1886; impede + -ance; term introduced by O. Heaviside
Related formsself-im·ped·ance, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

## Examples from the Web for impedance

### Historical Examples

• #### Impedance, however, does not equal the sum of resistance and reactance.

Physics

Willis Eugene Tower

• #### What is the impedance if the voltage of the line is 115 volts?

Physics

Willis Eugene Tower

• #### Impedance depends chiefly upon the frequency of alternation.

British Dictionary definitions for impedance

# impedance

noun
1. 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 ohmsSymbol: Z
2. a component that offers impedance
3. 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 waveSymbol: Z a
4. Also called: mechanical impedance the ratio of the mechanical force, acting in the direction of motion, to the velocity of the resulting vibrationSymbol: Z m
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

## Word Origin and History forimpedance

### n.

1886, from impede + -ance.

Online Etymology Dictionary, © 2010 Douglas Harper

impedance in Science

# impedance

[ĭm-pēdns]
1. A measure of the opposition to the flow of alternating current through a circuit. Impedance is measured in ohms. The resistance of a circuit to direct current (also measured in ohms) is generally not the same as its impedance, due to the effects of capacitance and induction in and among the components of the circuit. See also impedance matching.

impedance in Culture

# impedance

[(im-peed-ns)]

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