All Physics Faculty Publications

Document Type

Article

Journal/Book Title/Conference

American Journal of Physics

Volume

85

Issue

2

Publisher

American Association of Physics Teachers

Publication Date

2-1-2017

First Page

130

Last Page

134

DOI

10.1119/1.4973409

Abstract

We use simple symmetry arguments suitable for undergraduate students to demonstrate that the magnetic energy, forces, and torques between two uniformly magnetized spheres are identical to those between two point magnetic dipoles. These arguments exploit the equivalence of the field outside of a uniformly magnetized sphere with that of a point magnetic dipole, and pertain to spheres of arbitrary sizes, positions, and magnetizations. The point dipole/sphere equivalence for magnetic interactions may be useful in teaching and research, where dipolar approximations for uniformly magnetized spheres can now be considered to be exact. The work was originally motivated by interest in the interactions between collections of small neodymium magnetic spheres used as desk toys.

Comments

http://aapt.scitation.org/doi/abs/10.1119/1.4973409

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