. Effective resistance and inductance of iron and bimetallic wires . 0 1000 3000 Internal inductance (microhenrys per kilometer) 50 1411401127538 1451441127639 1511491157838 158 155 113 75 38 174 100 500 1000 3000 TABLE 12No. 10 Copper Clad R. M. S. current in amperes 3 5 Resistance (ohms per kilometer) Frequency: D. C 100 500 .. - 1000 3000 Internal inductance (microhenrys perkilometer) 50 19819817112245 20920817512341 22422217912243 244 100 , 240 500 181 1000 121 3000 40 Miller] Effective Resistan
. Effective resistance and inductance of iron and bimetallic wires . 0 1000 3000 Internal inductance (microhenrys per kilometer) 50 1411401127538 1451441127639 1511491157838 158 155 113 75 38 174 100 500 1000 3000 TABLE 12No. 10 Copper Clad R. M. S. current in amperes 3 5 Resistance (ohms per kilometer) Frequency: D. C 100 500 .. - 1000 3000 Internal inductance (microhenrys perkilometer) 50 19819817112245 20920817512341 22422217912243 244 100 , 240 500 181 1000 121 3000 40 Miller] Effective Resistance and Inductance 253 The results are plotted in Figs. 21, 22, and 23. For low fre-quencies there is an increase in resistance and inductance withincreasing current. This is due to an increase in the flux of induc-tion in the steel core which increases the inductance as a directeffect and increases the resistance indirectly on account of theskin effect. The latter tends to reduce the inductance, but isoutweighed by the direct effect. As the frequency increases the. ao Current In Amperes lao Internal Inductance iO sooov lOODV, -500^ ®?5 0 SE lOOV. 3L =J =^ •ft. Oip Current in Amperes 100 ResistanceFig. 21.—No. 4 copper clad wire resistance and inductance become independent of the currentstrength. This is due to the fact that the impedance of the corehas become so high relative to the impedance of the shell thatvery large changes in the former would be required to produceappreciable changes in the combined impedance. At very highfrequencies, of course, the copper clad wire would behave exactlythe same as a solid copper conductor. Similarly, the higher the 254 Bulletin of the Bureau of Standards [Vol. 12 conductivity of the copper-steel wire the less the dependance ofthe resistance and inductance upon the current strength, in thiscase also approaching as a limit the solid copper conductor. 2. A COMPARISON OF OBSERVED AND COMPUTED VALUES The experimental determ
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