Measurement of electrical resistivity via the effective magnetic susceptibility

Abstract

A simple method is proposed for contactless measurements of the electrical resistivity providing a direct digital readout. The method is based on the determination of the phase angle of the effective magnetic susceptibility of cylindrical samples in an axial AC magnetic field. The output voltage of a differential transformer is compensated by a voltage with a phase shift depending on the diameter of the sample, so that compensation becomes possible only at the magnetic-field frequency numerically equal to the resistivity of the sample.