In this paper, the boundary-value problem satisfying the Dirichlet condition has been solved for the case of a dielectric, spherical void inside a homoaeneous insulator by considering surface conductivity. Mathematical equations have been derived to calculate the respective electric fields E-i(t)and E-e(t) inside and outside spherical gas voids that exist within an insulator by considering the surface conductivity gamma(s) of gas voids having an electric permittivity of epsilon(i) and conductivity gamma(i) under DC (omega tau << 1) and AC (omega tau >> 1) conditions. The expression for the dipole moment of a polarized spherical dielectric particle has been obtained in accordance with the determined electric field Ei(t). The derived expressions are then applied to calculate reciprocal interaction force between the spherical particle and metallic electrodes. which is very considerable for the dielectric separation processes in the DC and AC cases. (c) 2007 Elsevier B. V. All rights reserved.