We derive an expression for the effective dielectric constant of a composite medium considering the contributions from both the electric and the magnetic dipole terms. We show that the form of the size distribution of small metallic particles determines the value of the volume fraction at which a sharp increase in ac absorption of a composite material occurs. Depending on the width and mode radius of the size distribution, the effective dielectric constant of a composite medium can be increased by several orders of magnitude.

• Received 11 June 1982

DOI:https://doi.org/10.1103/PhysRevB.27.5098