138 Crook — Electromagnetic Alternating Currents. 





Table 



II. 







Current density 

 per sq. mm. 

 



Total residual induction. 



For curve 1. For curve 2 



745 745 



2 



740 







712 



3 



743 







684 



5 



743 







665 



7-5 



740 







630 



9 



710 







580 



10 



695 







550 



15 



580 







360 



19-2 520 290 



Curve 2 (Diagram III) shows the corresponding effect due 

 to an alternating current passing through the iron strips in 

 multiple. 



Readings for these curves are found in Table III. 



Table III. 



Current density Total residual induction, 



per sq. mm. For curve 1. For curve 2. 



•0 722 722 



•28 719 710 



•56 714 701 



•84 708 689 



1-25 700 670 



1^68 690 654 



2-2 682 631 



2^5 675 618 



Second 3fethod. 



The second method of studying the alternating current 

 effect on hysteresis was carried out in the same way as the 

 first, the only difference being in the apparatus used. 



Instead of a number of narrow strips of iron connected in 

 series, the iron specimen was made from two thin sheets of 

 iron, separated by shellacked paper and rolled into a compact 

 tube. The iron sheets were each 56"'' long, 50^°^ wide and 

 •01 S*^"' thick. Along the edges of the plates corresponding to 

 the upper end of the tube were soldered 'Heading-in" con- 

 ductors, short distances apart. This was to insure a uniform 

 current density in all parts of the plate. The edges of the 

 plates at the other end of the tube were bared and soldered 

 together, so that a current entering the upper edge of one 

 plate would flow down, across the soldered junction, back on 

 the other plate and out by the leading-in conductors soldered 

 to its edge. 



