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impedance |
Also found in: Dictionary/thesaurus, Acronyms, Encyclopedia, Wikipedia, Hutchinson | 0.02 sec. |
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impedance /im·ped·ance/ (im-pēd´ans) obstruction or opposition to passage or flow, as of an electric current or other form of energy. Symbol Z . acoustic impedance 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. aortic impedance the sum of the external factors that resist ventricular ejection. impedance [impē′dəns] Etymology: L, impedire, to entangle a form of electric resistance observed in an alternating current that is analogous to the classic electric resistance that occurs in a direct current circuit. It is expressed as a ratio of voltage applied to a circuit to the current it produces, as an alternating current oscillates ahead of or behind the voltage. impedance obstruction or opposition to passage or flow, as of an electric current or other form of energy. acoustic impedance 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. Impedance Cardiac pacing The total opposition that a circuit presents to alternating electrical current. Cf Resistance. How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content. |
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Key statement: Measuring of curing conditions by dielectric or impedance means to produce a process curve which defines the correlation between the curve and the desired part properties. Although numerous authors have provided evidence of the usefulness of ASSR testing, their reports have concerned patients whose middle ear impedance measures were normal We report the cases of 2 patients who, following improvement of abnormal middle ear impedance values, experienced a marked improvement in measurable thresholds by ASSR testing. Some of these methods include back-EMF sensing, the addition of a sense winding in the motor, or measuring the impedance change of the motor windings by injecting current pulses or a high frequency sense carrier. |
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