Theory of four-point alternating current potential drop measurements on a metal half-space

摘要

An analytic expression describing the complex voltage measured between the pickup points of a four-point probe, in contact with the surface of a half-space conductor, is derived. The driving current is assumed to be time harmonic. There are two contributions to the measured voltage. One arises from the potential drop due to electric current flowing in the conductor. The other arises from induction in the loop of the pickup circuit. Both terms are obtained by integrating analytic expressions for the electric field, derived previously, along appropriate paths. Theory is compared with experimental data for co-linear and rectangular arrangements of the probe points, and very good agreement is obtained.