1971/02/01 by Jack B. Greene, Frank G. Karioris · 15 citations
Physics and Astronomy · #Analogy #Classical mechanics #Dipole #Electric dipole moment #Electromagnetism #Epistemology #Experimental and Theoretical Physics Studies #Formalism (music) #Magnetic dipole #Magnetic field #Physics #Quantum electrodynamics #Quantum mechanics #Theoretical physics #Vector potential
paper · doi:10.1119/1.1986086
published in American Journal of Physics 39(2), 172-175 (American Institute of Physics)
openalex publication_date 1971/02/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/26
In this paper we derive the expression for force on a magnetic dipole in an elementary way but without using “poles.” The equation F = (μ ·∇)B follows from concepts of electromagnetism already familiar to the first-year student. This is accomplished by working with forces on current elements and grouping terms to attain recognizable vector identities. In a similar manner, it is shown that the potential energy is U = −(μ·B). Introductory physics texts generally do not discuss force on dipoles. More advanced texts treat the problem by analogy to the electric dipole or by pure mathematical formalism which is beyond the level of the beginning physics major.