Theory of Dynamo-electrical Machines. 127 



C 



_ (M - € ,n)-^n(i+ i ^), 



i9 — 





(24) 



1+fti 



If for the sake of brevity we introduce in this the sign e f , with 

 the signification 



e'=e+^V, (25) 



the equations pass into 



£ . . (26) 



P 2 " = ^-f^. ( N + 6 '^ M ) + ^ M - 



I + pi v 



These equations we will use as the more general ones instead 

 of equations (23). For those machines in which the currents 

 induced in the iron core are too insignificant to be taken into 

 account, we need only put ?7 = 0, and therefore e'—e, in order 

 again to arrive at equations (23). 



§11. Application of the previous Equations to determining the 



work of the Ponder omotive Force and of the Electromotive 



Force. 



We now return to equations (17) and (18), which we have 



given in § 8 for determining the work of the ponderomotive 



force and electromotive force for the case in which the core is 



at rest, and of which the former must, according to § 9, be 



changed by replacing the product NP X by the product MP 2 . 



In these equations we replace the magnitudes P x and P 2 by 



the altered magnitudes P/' and P 2 // , so that the equations are 



If we replace P/' and P 2 " by their values given in (26), 

 the equations pass into 



f— MN( 4+ i^)«-*M.(, + <£)*, 



&. mn(/s+ I ^ r .)„_ p %_ 4W .(,+ ^y 



We have still to introduce in these equations the values 

 given for M and N in (12) and (13), that is, 



1 + #1* 



(28) 



