On Magnetic Forces and Work
Abstract
In this letter, we review a manifestly covariant Lagrangian formulation for the dynamics of a classical particle with intrinsic spin and elementary electric and magnetic dipole moments. We then couple the particle to the electromagnetic field, derive the appropriate generalization of the Lorentz force law, show that the particle's dipole moments must be collinear with its spin axis, and argue that the magnetic field does mechanical work on the particle's permanent magnetic dipole moment. As additional support for this last claim, we calculate the overall system's energymomentum and angular momentum from Noether's theorem and show that their local conservation equations lead to precisely the same force law. We conclude by computing the system's BelinfanteRosenfeld energymomentum tensor.
 Publication:

arXiv eprints
 Pub Date:
 November 2019
 DOI:
 10.48550/arXiv.1911.00552
 arXiv:
 arXiv:1911.00552
 Bibcode:
 2019arXiv191100552B
 Keywords:

 High Energy Physics  Phenomenology;
 High Energy Physics  Theory;
 Physics  Classical Physics
 EPrint:
 5 pages, no figures