Behaviour of Iron under Small Magnetizing Forces. 245 

 Statical Permeability for different Inductions. 



B 



12-9 



521 



144-2 



228-0 



389-3 



6085 



9200 



H 



•0747 



•2450 



•5334 



•7467 



1-0671 



1-3903 



1-7097 



/* 



172-6 



212-5 



270-3 



305-4 



364-8 



437'7 



538-1 



From the tables it appears that the wave form of the 

 magnetizing current is nearly sinusoidal, and so the induction 

 may be considered as that produced by magnetizing currents 

 of similar wave-form. 



The relation between fi and B x is exhibited graphically in 

 fig. 3 (upper curves). These curves show that for any one 

 frequency the value of fi diminishes as the induction is 

 decreased, the decrease becoming more and more rapid as 

 the induction get slower. If /jl is plotted against H^ how- 

 ever, it is found that, as for the bundle of wires, the portions 

 of the curves for low values of H 1 are approximately straight 

 lines, but the range over which this is true is much more 

 limited for the rod than for the wire bundle, extending in 

 the former only to about H = 0*3. The curves appear to 

 approach a definite limit for each particular frequency when 

 the value of the induction becomes very low. It is seen also 

 that the frequency has a marked effect on the value of /x , an 

 increase in frequency being accompanied by a decrease 

 in /i , the decrease being more marked for the higher 

 frequencies. 



On the same diagram is shown the relation between the 

 statical permeability fi and the induction. 



6 also decreases as the induction is decreased, the rate of 

 decrease becoming more and more rapid as the induction 

 becomes lower (tig. 4). For each frequency, 6 seems to 

 approach a definite value when the induction is very low. 

 Also an increase in the frequency is accompanied by an 

 increase in 6. 



The limiting values of 6 and fx obtained from the curves 

 satisfy fairly well the equations obtained in § 3. The values 

 used have been 



e 



O 



5 



o 



11-8 



o 



19-6 



o 



32 



Pr 



155 



150 



142 



119 



ft) 



53-2 



96-1 



172-6 



349-1 



