A Measurement of the Force between Two Current-Carrying Wires

The measurement of the force acting between two parallel, current-carrying wires is known as Ampère's experiment. A mechanical balance was historically employed to measure that force. We report a simple experiment based on an electronic precision balance that is useful in clearly showing students the existence of this interaction and how to measure it. The ampere (A) is one of the fundamental quantities of the international system of units, defined only on the basis of the force acting between a pair of parallel wires through which current is flowing.