Thermodynamic equilibrium in dielectric fluids

A rigorous deduction of the thermodynamic-equilibrium condition is provided for a homogeneous, uncharged and linear dielectric fluid contained in an electrostatic field. Contrary to the previous ones, this deduction does not postulate the existence of a mechanical stress tensor and of a body force density in the polarized fluid. Then, the equilibrium condition is employed to obtain the mass density distribution of the fluid and to present a correct proof of the well-known formula for the attractive force between the plates of a plane-parallel capacitor immersed in the fluid. © 1994 Società Italiana di Fisica.