ANALYSIS OF PULL AND MAGNKTIZATION MEASUREMENTS 101 



Table II — Evaluation of Magnetic Circuit Constants 



The points of langcucy arc iiuUcatod on the pull curves of Fig. II. 

 These values of 5 have been marked on the corresponding curves of Fig. 

 8, from which can be determined the corresponding values of ^c , and 

 thus of -Je ■ It may be noted in passing that these values of Jc are all 

 similar, corresponding to a mean level of about 24 ampere turns, or 30 

 gilberts. The magnetization results gave vahies of 4,000 maxwells for 

 ^' (Fig. 3) and of 0.007 cm"^ for (Re (Table I), giving a value of 28 

 gilberts for the product. This agrees with the value of Jc at the tangent 

 points of the pull curves, showing that these points coincide with the 

 points of minimum reluctance ((p = if'). 



Taking the ratio of Se to ^ as read from the curves of Fig. 8 at the 

 indicated tangent points, the values of ^/(■iiir-y/F') in Fig. 12 have been 

 multiplied by the corresponding values of 'Je/'^, giving the points indi- 

 cated by triangles in this figure. These conform to a straight line relation, 

 in agreement with (19). The slope and intercept of this linear plot have 

 been used to determine the values of (R02 and ^42 listed under "Pull 

 Results" in Table II. 



The four quantities determined from the two plots of Fig. 12 appear 

 in the three independent equivalence equations (7), and these three 

 equations may therefore be used to determine the other three quantities : 

 (Rl , (Rl2 , and (Re • The resulting values of these latter quantities are 

 listed under "Pull Results" in Table II. For comparison, the table in- 

 includes the corresponding values of these quantities obtained from the 

 magnetization measurements, and given previously in Table I. The 

 agreement between the results derived from these different kinds of 

 measuroments indicates the validity of the analysis described here. 



High Domtt/ Pull 



As previously noted, it is convenient to express the pull F in the high 

 density region in terms of the ratio F'/F, where F' is the pull computed 

 from (13) for the \alue of ;T applying. F' 'F is readily evaluated from a 

 logarithmic plot of the observed pull versus ^7, as illustrated by Fig. 11. 



