136 Crook — Electromagnetic Alternating Ourrents. 



The curves were taken in the order in which they occur on the 

 plate and were plotted from the readings given in Table I. 



Curve 1 is the normal hysteresis cycle. 



Curve 2 is a cycle taken with an alternating current density 

 in the iron to 10 amperes per sq. mm. 



Table I. 







B. 





H. 



Cycle 1. 



Cycle 2. 



Cycle 3. 







174 



120 



1443 



3-15 



846 



600 



1815 



6-3 



2447 



2010 



3252 



9-45 



4329 



4245 



4890 



12-6 



5400 



5415 



5706 



15 75 





6279 





18-9 



6765 



6750 



6939 



25-2 



7500 



7440 



7703 



31-5 



7590 



7686 



7740 



25-2 



7594 



7fc04 



7689 



18-9 



7311 



7275 



7320 



12-6 



6675 



6630 



6600 



6-3 



5730 



5655 



5331 







3285 



3128 



2232 



6-3 



-2418 



— 2550 



-3525 



12-6 



— 5750 



— 5750 



-6600 



18-9 



— 6999 



-6747 



-7011 



25-2 



-7677 



-7446 



— 7560 



31-5 



— 7983 



-7800 



-7920 



25-2 



—7794 



-7650 



-7776 



18-9 



— 7560 



-7360 



— 7440 



12-6 



-7215 



— 6086 



— 6981 



6-3 



— 6204 . 



— 5765 



— 5607 







-4050 



-3666 



-2265 



0-3 



1863 



2100 



3249 



A close inspection of the curves will show that the reduction 

 of the area of the cycle is directly proportional to the reduction 

 of the width and also to the reduction of the residual mag- 

 netism remaining in the iron when the magnetizing force is 

 reduced to zero. This being the case, the problem can be 

 considerably simplified by studying the effects of the alterna- 

 ting current on the residual magnetism from a constant mag- 

 netizing force, assuming that the effect on the hysteresis cycle 

 is directly proportional to this effect on the residual mag- 

 netism. 



The curves in Diagram II were taken to show the effect on 

 the residual magnetism of varying current density in the iron 

 strips in series. They were plotted from the readings given 

 in Table II. Ordinates represent total induction and abscissae 



