The practical unit of electrical current; the absolute, practical a. originally was defined as having the value of 1/10 of the electromagnetic unit (see abampere and coulomb). Present definitions are:
1. The practical unit of electrical current; the absolute, practical ampere originally was defined as having the value of 1/10 of the electromagnetic unit (see abampere and coulomb.
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.
Origin
[A. Ampère]