Effects of small inclusions in a dielectric medium, the production of field nonlinearities by embedded particles can be illustrated by considering the limiting case of a single particle of radius R in an otherwise uniform field. The field distribution in both the external medium and the particle are defined by Laplace's equation, ∆²Φ = 0, and by the boundary condition on the sphere surface ε_s (δ_r ∙ ∆Φ_s) = ε_c (δ_r ∙ ∆Φ_c) here the indices s and c stand for sphere and continuum, respectively.