Document Type



The Oersted effect explains the magnetic field surrounding a conductor carrying an electric current. In January 19 5 7 Galel reported that ferromagnetic wires carrying d.c. currents have their magnetizations changed and in addition to the current-field there is a change in the field set up by the re-orientation of the domains in the wire. The motion of the domains at the inception and interruption of a direct current in the wire can be shown by surrounding the wire sample with a search coil. The motion of the domains induces a voltage in the search coil similar to the Barkhausen effect, but in this case produced by the current in the sample itself. Figure one shows a photograph of the flux change on the "make" and "break" recorded by means of a Sanborn recorder. The ripple is 60 cycle. Evidence indicates that these voltage changes are closely related to the magnetic properties of the sample and disappear at the Curie point. Alternating current sent through the wire sample induces continuous a.c. in the pick up, the wave form depending upon the shape of the hysteresis loop of the material. Figure two shows the alternating voltages picked up by the search coil surrounding a nickel wire on an oscilloscope, as a function of temperature. In order to test the hypothesis that the electric current magnetizes the wire, tests of the internal friction losses and magnetostriction were undertaken by George Sullivan as a Senior Honors project. This paper reports the results on the internal friction losses.

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Proceedings of the Iowa Academy of Science





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©1957 Iowa Academy of Science, Inc.



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