5 -A] STUDY AND OPERATION. J 45 



Sd<f> = max . sin <at dt ; 



E E 



<f> = - m "' cos w/= ^ sm (CD/ 907. 



The maximum value of the flux is 

 and the flux per unit area is 



^max. = 0max. -~ A = ~~^~T~ 



To express in terms of effective voltage, substitute V^ for max .. 

 Multiplying by io 8 to change from C.G.S. units to volts, and remem- 

 bering that w is 27r times the frequency (), we have as a working 

 formula for flux density 



max - 



It follows from this formula that a constant potential transformer 

 is a constant flux transformer. It also follows that, if a certain flux 

 is maintained in the transformer, the voltage in any coil is propor- 

 tional to the number of turns in that coil. For further interpreta- 

 tion, see 24-26. 



35. Without Sine Assumption. We have the fundamental rela- 

 tion 



d < = edt/S. 



Integrating for half of a period T, during which time the flux changes 

 from a minus to a plus maximum, 



'+* J i A ,, 

 ^=0 L i 



Writing i/n for T, and multiplying by io s to reduce to volts, we 

 B A - 8 



#max. >max.-v-' 



This is true of any shaped electromotive force wave, of which E &v is 

 ii 



