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Graphs of the induced magnetic moment and shielding effect of a spherical shell in a uniform magnetic field

1947; Volume: 52; Issue: 3 Linguagem: Inglês

10.1029/te052i003p00369

2379-5697

Bryant Tuckerman,

Nuclear Physics and Applications

This paper presents graphs of well‐known formulas for the induced magnetic moment and shielding effect of a spherical shell of constant permeability introduced into a uniform magnetic field. The problem is of interest in the theory of the deviations and compensation of the magnetic compass, and in the shielding of electromagnetic instruments from external magnetic fields. Barlow [see 1 of “References” at end of paper] in an experimental investigation of the deviations of a compass produced by spherical balls and shells, concluded, “... the tangents of the deviation are proportional to the cubes of the diameters, or as the 3/2 power of the surface, whatever may be the weight and thickness ... . This law, however, I have since found to have its limits; ... the magnetic fluid requires a certain thickness of metal, exceeding 1/30 inch, in order effectually to develop itself, and to act with its maximum of effect.” The latter conclusion was based on work with ten‐inch spheres.