On the interaction between a current density and a vector potential: Ampère force, Helmholtz tension and Larmor torque.

Germain Rousseaux (1)

1 INLN - Institut Non Linéaire de Nice Sophia-Antipolis

We present a review of the works describing the origin of a magnetic torque. We show that its more general expression makes intervene the vectorial product of the current density and the vector potential. We relate this Larmor torque to the Ampère force and more specifically to the Helmholtz mechanical tension, which is at the origin of the longitudinal stresses in "open" circuits carrying current. The Ampère force enters into the realm of Newtonian Electrodynamics and we explain the absence of contradiction with special relativity.

Mots clés: vector potential; magnetic torque; Ampère force; Helmholtz tension; Larmor torque; stress-energy tensor

Domaines: Physique Classique [physics.class-ph]; Physique Générale [physics.gen-ph]; Histoire de la Physique [physics.hist-ph]; Enseignement de la physique [physics.ed-ph]

Germain Rousseaux. On the interaction between a current density and a vector potential: Ampère force, Helmholtz tension and Larmor torque.. 2005. ⟨hal-00004437v2⟩