A Null Method for Testing Magnetic Properties of Materials

Abstract

A description is made on the theory, construction and the operation of the permeameter devised by the writer as well as some experimental studies on it. The permeameter is a double bar and double yoke type. The reluctance of the yoke and gaps are compensated by the magnetising coils on the yoke which are excited and regulated independently. The criterion of the proper compensation is the condition that the magnetomotive force applied between two fixed points in the specimen is exactly consumed by the magnetic reluctance at that portion. This condition is confirmed by proving that the magnetic potential difference between those two points is zero.
Experiments show that the permeameter gives satisfactory results in the measurement of magnetic properties of solid and sheet materials of iron and steel. The accuracy and the consistency of the readings taken at different times exceed all that is required by most of the commercially precise magnetic measurements.