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Pronunciation: am′pēr


  1. The practical unit of electrical current; the absolute, practical ampere originally was defined as having the value of one tenth of the electromagnetic unit.
  2. Legal definition: the current that, flowing for 1 second, will deposit 1.118 mg of silver from silver nitrate solution.
  3. Scientific (SI) definition: the current that, if maintained in two straight parallel conductors of infinite length and of negligible circular cross-sections and placed 1 m apart in a vacuum, produces between them a force of 2 × 10−7 N/m of length.

See: abampere, coulomb

[André-Marie Ampère]

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© Copyright 2018 Wolters Kluwer. All Rights Reserved. Review date: Sep 19, 2016.