Magnetic Hysteresis witJi Frequency, 



1 09 



In the case of magnetization by means of alternating 



currents, it is fair to assume that the static hysteresis will 

 depend on the maximum value of B. (B say), during the 



Fig. 2. 



r\ 



W% 



2 ' 5 5000 7 " 5 10000 -B max.- 



Steiumetz Coefficient a v. Max. Induction (U = crB 1 " 6 ). 



alternation. B„ is obtained from the maximum /3 reading by 

 multiplying the latter by b (see § 6), and 



U = <rB ", 



in which for a we take from the curve in fig. 2 for the ring 

 used the value corresponding to B . 

 For the experiment being discussed, 



Max. /3 = tf = 20l (see §5) 



B = 17-52£ = 3522 (see §6), 



for which induction for ring I. 



a = "002012. 



hence 



U = 952. 



9. No formula is available by means of which the eddy- 

 current loss in an annular lamina can be exactly determined, 

 but a fair approximation to it can be obtained in the following- 

 way. 



Searle and Bedford* have shown that if X be the space 

 average of the heat dissipated in a thin strip by eddy- 

 current-. 



• Phil. Trans, vol. exeviii. 



