Contactless Induction Method for Electric Resistivity Measurement

Abstract

A new absolute method is developed for measuring electric resistivity in the range of 10⁻⁸ to 10⁺⁸ Ω cm of a sample of almost arbitrary shape. This method takes into account the effect of self‐induced conduction and polarization current. Measurements are made with the specimen placed in a constant rotating magnetic field in such an orientation that it experiences maximum torque and has minimum moment of inertia. This can be shown to be the same orientation for which, if the specimen were free to rotate, it would reach the angular velocity of the rotating field in minimum time. This method is applicable to homogeneous and isotropic conducting materials in both solid and liquid states, including ferromagnetic substances. The mathematical formula for the measured torque is developed and the technique for measuring electric resistivity is explained.