. Effective resistance and inductance of iron and bimetallic wires . t results for circular magnetization,it was found to be necessary to demagnetize the iron wire carefullyjust as is necessary in measurements of axial magnetization. Thisis illustrated in the curves in Fig. 3, which show two sets of deter-minations of Li as a function of / for a soft-iron wire (No. 43 SteelWire Gage). The first set was taken without any attempt to Miller] Effective Resistance and Inductance 221 demagnetize the wire, and the results are plotted by closed taking the next set the wire was demagneti
. Effective resistance and inductance of iron and bimetallic wires . t results for circular magnetization,it was found to be necessary to demagnetize the iron wire carefullyjust as is necessary in measurements of axial magnetization. Thisis illustrated in the curves in Fig. 3, which show two sets of deter-minations of Li as a function of / for a soft-iron wire (No. 43 SteelWire Gage). The first set was taken without any attempt to Miller] Effective Resistance and Inductance 221 demagnetize the wire, and the results are plotted by closed taking the next set the wire was demagnetized by reducingthe current in the wire slow^ly from 4 amperes to o. i ampere withthe secohmeter running. The results of the second set are plottedby open circles. The curves show the same characteristics as theinduction curves obtained by Burrows ^^ in investigating the effectof imperfect demagnetization in ordinary magnetic measurements;i. e., considerably higher values of the magnetic induction for thedemagnetized wire in the region where the curve is steep, but. Current in Amperes Fig. 3.—Effect of demagnetization practically no difference in the values after the knee of the curveis reached. Having obtained a curve for Li, tangents to the curve were drawn at a number of points and values of -— determined. Then fi was calculated from equation (2) and plotted as a function of H. 2. DETERMINATION OF THE PERMEABILITY FOR AXIAL MAGNETIZATION In order to compare the permeability for circular magnetizationwith that obtained when the wires were magnetized axially, meas-urements were also made upon the wires by the ordinary ballistic This Bulletin, 4, p. 205; 1907 (Scientific Paper No. 78). 222 Bulletin of the Bureau of Standards [Voi. 12 method.^2 The wires were a meter or more in length and themagnetizing coil was 115 cm long and cm in diameter, witheight tmns to the centimeter. The test coil had a single layerof 1000 turns of No. 32 enameled wire wound on a glass tube andw
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