PRINCIPLES OF ALTERNATING CURRENT 



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force must be just equal and opposite to OE and is shown 

 at OF. The angle of phase difference between the voltage 

 and current is cj> and, in this circuit, it is seen that the 

 current leads the voltage. To find the magnitude of / 

 we use the equation of reactions 



(53) 



this to be vector addition. 



FIG. 134. Vector Diagram of Forces of Circuit in Fig. 133. 

 In ordinary arithmetical form we have 



E 2 =JR 2 +(2KfLI-^--} 2 ', . . . (54) 



(55) 



or 



E 



=F|. (56) 



This expression has sometimes been called Ohm's law for 

 the alternating current circuit. 



