Mechanisms of electrostatic interactions between two charged dielectric spheres inside a polarizable medium: An effective-dipole analysis

TL;DR

This paper investigates electrostatic interactions between charged dielectric spheres in a polarizable medium using an effective-dipole model, revealing polarization-induced repulsion at close distances when the medium's dielectric constant exceeds that of the spheres.

Contribution

It introduces an effective-dipole analysis to explain how polarization effects can cause repulsion between charged spheres at short range, a novel insight into dielectric interactions.

Findings

Polarization-induced opposite-charge repulsion can occur at short distances.

Repulsion depends on the dielectric constant of the medium being higher than that of the spheres.

Effective-dipole analysis explains counterintuitive charge separation behavior.

Abstract

The mechanisms of electrostatic interactions between two charged dielectric spheres inside a polarizable medium have been investigated, in terms of hypothetical effective dipoles that depict how the positive and negative charge in each particle are separated. Our findings, which revealed that it is possible for polarization-induced opposite-charge repulsion to occur at short interparticle separations if the dielectric constant of the medium is greater than the dielectric constants of both spheres, provide insights into the physics of charge separation in each sphere and of polarization in the medium behind such counterintuitive behaviour.