ALTERNATI\<; d'RRENT AND V 



11 



of the wave. The form factor of a sine wave is 1.11. The 

 maximum, effective, and average values for a sine wave of voltage, 

 whose r.m.s. value is 100 volts, are shown in Fig. 8. 



*.* 



Fio. 8. Relation of maximum, effective, and average values of a sine wave. 



6. Equation of Sine Wave of Current. If wt is substituted 

 for ./ in ('(niation (1), Par. 2, the equation of a sine wave of 

 alternating-current is given by 



i = I max sin at (3) 



where / is t he value of the current at any time, t, I mat is the maxi- 

 mum value of the current, and co = 2irf. The term co is equal to 

 2-Tr times the frequency /, and is the tnttjulnr rclociti/ in radiant 

 cond of the rotating vector which may be used to construct 

 the wave. (Appendix, page 453.) 



Similarly, the equation of a sine wave of electromotive force 

 will be given by 



e = -i co/. (4) 



What i* theequation of :i 'J ."-> d rii iTdi t . , h:i V ing all 



fffcctivc value of ;{() a in p. , and u hat is tlir value. /', of tin- current \vlirn the 



B CrOSSeS the til D a positive (lirertloli 



'! the time is equal to /, 



te \ * 



Ima* = 30V'2 = 42.1 amp. 



2*25 = 157 = o> 



t - 42.4 sin i:,7 /. .Irw. 



i' - 42.4 sin i 



<i 7s.". ra.l 



2r - 6.28 radians - 360 (page 463) 



