Ampere tension in electric conductors

It is shown that the application of the Ampere and Lorentz force laws to a closed current in a metallic circuit results in two different mechanical force distributions around the circuit. In addition to the transverse forces, which both laws predict, the Ampere electrodynamics requires a set of longitudinal forces that subject the conductor to tension. These longitudinal forces explain electromagnetic jet propulsion and the recoil mechanism in a railgun. Pulse current experiments are described in which Ampere tension shattered solid aluminum wires. Electrons moving through the metal lattice are the basic current-elements of the Lorentz force theory. But Ampere assumed his current-elements to be infinitely divisible. With the help of computer-aided analysis and experiment, it is demonstrated that the amperian current-element must also be of finite size and involve at least one lattice ion in addition to the conduction electron. Calculations with Ampere´s formula have been found to give reasonable results when the atom, or unit atomic cell, is taken to be the smallest possible current-element. Some technological consequences of Ampere tension are discussed briefly with regard to pulse currents in normal conductors and steady currents in superconductors. The use of large macroscopic current-elements of unit length-to-width ratio gives rough approximations to the Ampere tension. The accuracy of the calculations can be improved by resolving the conductor into a number of parallel filaments, each filament being subdivided into cubic current-elements.