Electromagnetic radiation and the self torque of an oscillating magnetic dipole

Masud Mansuripur; Per K. Jakobsen

doi:10.1117/12.2569137

25 August 2020 Electromagnetic radiation and the self torque of an oscillating magnetic dipole

Masud Mansuripur, Per K. Jakobsen

Proceedings Volume 11462, Plasmonics: Design, Materials, Fabrication, Characterization, and Applications XVIII; 114620W (2020) https://doi.org/10.1117/12.2569137
Event: SPIE Nanoscience + Engineering, 2020, Online Only

Abstract

A uniformly-charged spherical shell of radius R, mass m, and total electrical charge q, having an oscillatory angular velocity Ω(t) around a fixed axis, is a model for a magnetic dipole that radiates an electromagnetic field into its surrounding free space at a fixed oscillation frequency ω. An exact solution of the Maxwell-Lorentz equations of classical electrodynamics yields the self-torque of radiation resistance acting on the spherical shell as a function of R, q, and ω. Invoking the Newtonian equation of motion for the shell, we relate its angular velocity Ω(t) to an externally applied torque, and proceed to examine the response of the magnetic dipole to an impulsive torque applied at a given instant of time, say, t = 0. The impulse response of the dipole is found to be causal down to extremely small values of R (i.e., as R → 0) so long as the exact expression of the self-torque is used in the dynamical equation of motion of the spherical shell.

Conference Presentation

Citation Download Citation

Masud Mansuripur and Per K. Jakobsen "Electromagnetic radiation and the self torque of an oscillating magnetic dipole", Proc. SPIE 11462, Plasmonics: Design, Materials, Fabrication, Characterization, and Applications XVIII, 114620W (25 August 2020); https://doi.org/10.1117/12.2569137

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