Notes on a New Method for the Determination of the Magnetic Flux Density and Permeability

The method described gives a ready means for determining the magnetizing force, the corresponding flux density, and permeability at any wave length whatever. In taking a series of readings for different ampere-turns and at a definite wave length, we may obtain (a) the magnetization curve, (b) the permeability-ampere-turns curve. Since the suggested arrangement applies to any practically available wave length we have a convenient means to compare the Bmax-values for very long wave lengths with the corresponding values determined at higher frequencies, and thus obtain a clear insight into the skin action of an iron core. In a similar way the permeability-wave length curve may be found for a definite number of ampere turns. The method simultaneously determines either the total losses of the test sample or the losses due to direct current resistance, skin effect of the conductor, hysteresis and eddy currents in the iron core separately, and there can be obtained the (a) watts/unit volume-wave length curve for a certain number of ampere turns, (b) watts/unit volume-flux density curve at a constant wave length, and (c) watts/unit volume-thickness of laminations curve for a constant wave length and a constant number of ampere turns; which enables the investigator to ascertain all the conditions which are necessary for determining the desired properties of any radio frequency apparatus containing a ferro-magnetic medium. Moreover, by means of equations (14) and (15) one is able to experimentally investigate the dependance of the magnetizing force and permeability on the frequency.