Fields and forces of a macroscopic sphere above a ground plane in a sinusoidally varying electric field

Expressions are developed for the electric fields in and around a sphere of arbitrary conductivity and permittivity. The sphere is suspended in a fluid (also of arbitrary conductivity and permittivity) above a conducting grounded electrode with an applied field that varies sinusoidally in time. The force on the sphere is evaluated and typical results are presented. In the low- and high-frequency limits, the magnitude of the force is independent of frequency and can be represented on a single normalized graph. The results can be applied to two identical spheres in an axial electrical field (using symmetry) and to two permeable spheres in an axial magnetic field (by duality).