Theory of an electromagnetically levitated metal sphere. I - Absorbed power

The power absorbed in a nonferromagnetic conducting sphere exposed to an external, time-varying magnetic field is analytically calculated. The external magnetic field is generated by a set of sinusoidally alternating, but otherwise arbitrary, current density fields with different frequencies. The special cases of rotational symmetry in the system and of circular current loops are also treated. The underlying quasistatic Maxwell equations are solved by expansion in spherical harmonics and Bessel functions.