Quincke Rotation of Spheres

The spontaneous rotation of small spherical and cylindrical objects immersed in liquid dielectrics and subjected to strong electrostatic fields was first recorded by Quincke in 1896. The rotation was found to be threshold-dependent; and certain conditions on the relative conductivities of the liquid and solid particles were discovered necessary for the effect to be observed at all. A review of the literature shows that Quincke rotation has been rediscovered, renamed, and reexplained several times since the original work. Not all published analyses are correct. A very simple solution of the problem is described which nses the effective dipole concept. The relevance of Quincke rotation to various problems in dielectrophoresis (DEP), conduction in liquid dielectrics, etc., is discussed, and a few practical implications are considered.