Dependence of the dielectric properties of suspensions on the volume fraction of suspended particles

The fundamental expression for the complex permittivity εs∗ of a dilute suspension of particles in a suspending medium εe∗:εs∗=εe∗(1+3ϕd∗) is strictly valid for any value of the volume fraction ϕ, provided that the dipolar coefficient d∗ is interpreted as the ensemble average value of the particles and is defined in terms of the macroscopic electric field in the suspension.