impedance

== English == === Etymology === From impede +‎ -ance. In sense 2 and sense 3 it was coined by English mathematician and physicist Oliver Heaviside in 1886. === Pronunciation === (Received Pronunciation) IPA(key): [ɪmˈpiːdn̩s] (General American, Canada) IPA(key): [ɪmˈpidn̩s] (General Australian) IPA(key): [ɪmˈpiːdn̩s] === Noun === impedance (countable and uncountable, plural impedances) The act of impeding; that which impedes; a hindrance. (physics) A measure of the opposition to the flow of an alternating current in a circuit; the aggregation of its resistance, and inductive and capacitive reactances; the ratio of voltage to current treated as complex quantities. (physics) A quantity analogous to electrical impedance in some other energy domain (physics, usually with “mechanical”) a measure of opposition to motion of something subjected to a force; the ratio of force to velocity treated as complex quantities. (physics, usually with “acoustic” or “sound”) the ratio of sound pressure to volume flow rate treated as complex quantities. ==== Usage notes ==== in technical works, "impedance" is universally given the symbol Z, which is often used as a synonym for the word even in running text. ==== Derived terms ==== ==== Related terms ==== impediment ==== Translations ====