ALTERNATING CURRENT AND VOLTA( 21 



mine the voltage across their open ends if they are connected together at 

 O as shown. 



Let Eoo and E^ Fig. 18 (6), represent the respective voltages across coils 

 aO andOb. Combining these two vectorially, the voltage Eat, is obtained. As 

 Eao and <* are at right angles, their resultant is readily found. 



E ab = \/Eo 2 + o6 2 = Vl60 2 + 160 2 = 226 volts. Ans. 



It must be kept constantly in mind that alternating voltages and 

 current* /////*/ In eomhineti nctorially. 



The only occasions when aritlunotical addition is permissible 

 are when the voltages or the currents are in phase. 



