ELECTROMOTIVE FORCE AND CURRENT. 



17 



the number of volts and the number of amperes were very 

 different. 



The circuit in which the current flows has a self-induction 

 of 5 milli-henries = -005 henries. 



The change of current will produce an electromotive 

 force of self-induction in the circuit which must also be 

 overcome by the alternator supplying the circuit in order 

 that the current c may be maintained. This electromotive 

 force is an alternating electromotive force J period in advance 

 of the current. The curve representing it might be obtained 

 by drawing a curve similar to Curve II. in Fig. 6, and then 



FIG. 7. CURVES OF CURRENT AND COMPONENT AND TOTAL K.M.F. 



multiplying each ordinate by n L, a, more direct way is the 

 following. It has already been pointed out that the maximum 

 value of the electromotive force of self-induction = 2 TT n C L, 

 when C is the maximum value of the current, and that the 

 curve representing this electromotive force is J period in 

 advance of the current in phase. Consequently, we may 

 directly draw a sine curve having a maximum value of 

 2-irnLC and J period in advance of the curve of current. 



