A New Role for the Electrophorous

Abstract

THE electrophorous¹ consists of a flat polymeric plate placed in contact with a flat metal plate. The two surfaces are separated only by the higher asperities of the surfaces and so actual contact is only made at a few points. If the polymer surface has been previously negatively charged by the diffusion of electrons into it, then the metal will be negatively charged at the few places where contact is made and positively charged by induction where there is no contact. If a time-varying dynamic load is now applied to the system so that the plates never lose contact and the variation of the distance between them is due to the elastic deformation of the asperities, then there will be time-dependent variations in the induced electrostatic charge on the metal plate. If the induction effects predominate, then it is of interest to measure the current flow to, and from, the plate when it is connected to earth through a high-resistance voltmeter or oscilloscope.