Discussion on magnetic properties of iron at frequencies up to 200,000 cycles. New York, November 13, 1911. (see proceedings for December, 1911)

Harold Pender: I should like to call attention to the fact that the results of this paper are confirmed by some experiments which were performed at the Institute of Technology last year under my direction by F. B. Silsbee. The method used was entirely different. For the high frequency generator we used an arc giving a frequency something like 200,000 cycles per second. This frequency was impressed upon a primary winding on a small iron core made up of very fine iron wire, and the electromotive force induced in a secondary winding on the same core was measured. This secondary induced electromotive force was also calculated on the assumption that the true permeability is independent of the frequency. In making this calculation the proper allowance was made for the non-uniform distribution of the flux in the core, usually referred to as the magnetic skin effect. The measured and calculated electromotive forces were found to agree quite closely.