TABLE OF CONTENTS. 



CHAPTER I. PAGE. 



ALTERNATING ELECTROMOTIVE FORCE AND CURRENT . . . . 1 



General laws ; production of electromotive force ; 

 relation between current and magnetic field ; nature 

 of electromotive force produced by an alternator ; 

 voltage and frequency of an alternator ; electromotive 

 force of self-induction ; coefficient of self-induction : 

 resultant electromotive force in a circuit ; angle of lag ; 

 vector diagrams ; resultant of two vectors ; resultant 

 voltage of two alternators ; determination of angle of 

 lag by three voltmeters. 



CHAPTER II. 

 IMPEDANCE 34 



Impedance diagram for circuit ; determination of 

 dependence of impedance upon resistance, frequency, 

 air-gap, and strength of current ; graphic calculation oi 

 impedance ; impedance of resistance coils ; determina- 

 tion of impedance of an armature. 



CHAPTER III. 



POWER AND POWER-FACTOR 56 



Curves of current, volts, and watts ; power-factor ; 

 determination of power-factor ; energy and idle voltage 

 and their calculation ; function of choking coil, deter- 

 mination of power saved by its use ; determination of 

 voltage of choking coil required for an arft lamp ; 

 resultant of two currents not in phase, experimental 

 determination ; determination of idle and energy 

 currents ; measurement of power by 3-voltmeter and 

 3-ammeter methods. 



