Lorentz torque on a charged sphere rotating in a dielectric fluid in the presence of a uniform magnetic field

The Lorentz torque exerted by a uniform magnetic field on a charged sphere rotating steadily in a dielectric fluid is calculated to first order in the charge. For a strongly polar fluid and stick boundary conditions the torqu e is enhanced significantly with respect to its vacuum value. The modificat ion from the vacuum value depends only on the static dielectric constant of the fluid and on the slip parameter. It is independent of the dielectric r esponse of the sphere and of the shape of the radial charge distribution. T here is a nonvanishing Lorentz torque, even when the charge is concentrated in the center of the sphere.