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[ree-ak-tuh ns] /riˈæk təns/
Electricity. the opposition of inductance and capacitance to alternating current, expressed in ohms: equal to the product of the sine of the angular phase difference between current and voltage and the ratio of the effective voltage to the effective current. Symbol: X.
Acoustics. acoustic reactance.
Origin of reactance
First recorded in 1890-95; react + -ance Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for reactance
Contemporary Examples
Historical Examples
  • reactance is the effect of self-induction in hindering the flow of current.

    Physics Willis Eugene Tower
  • The combined effect of resistance and reactance is called impedance.

    Physics Willis Eugene Tower
  • Impedance, however, does not equal the sum of resistance and reactance.

    Physics Willis Eugene Tower
  • The degree to which the current is opposed by the capacity is the reactance of that capacity for that frequency.

  • The degree in which any current is opposed by inductance is termed the reactance of that inductance.

  • Find the reactance of a choke coil having a resistance of 10 ohms, when its impedance is 50 ohms.

    Physics Willis Eugene Tower
  • The light obtainable through a reactance is not of the best quality and reactances are not much used.

  • If a reactance is used in place of a rheostat in an alternating-current circuit, the loss of energy is greatly reduced.

  • The essential parts of a Tungar Rectifier are: A bulb, transformer, reactance, and the enclosing case and equipment.

British Dictionary definitions for reactance


the opposition to the flow of alternating current by the capacitance or inductance of an electrical circuit; the imaginary part of the impedance Z, Z = R + iX, where R is the resistance, i = √–1, and X is the reactance. It is expressed in ohms Compare resistance (sense 3)
the opposition to the flow of an acoustic or mechanical vibration, usually due to inertia or stiffness. It is the magnitude of the imaginary part of the acoustic or mechanical impedance
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
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