THE TRANSFORMER. 129 



the experiments which follow, and a special experiment for 

 this purpose is therefore not given. 



Voltage Drop in Transformer. The current flowing in 

 both primary and secondary windings requires a certain 

 amount of voltage to be spent in overcoming the resistance 

 of these windings. Let ' "'-' : 



c 1 = current in primary winding, t- 

 . c 2 = current in secondary winding. 



r 1 = resistance in primary winding. 



r 2 resistance in secondary winding. 



T l = number of primary turns. 



T., = number of secondary turns. 



The loss of voltage in primary windings due to their 

 resistance = C A r x volts. 



The effect of this drop is to make the effective voltage spent 

 in producing the alternating flux in the core smaller by this 

 amount. Consequently, if e^ = primary applied voltage, the 

 effective voltage which produces the flux affecting the 

 secondary winding e 1 <<* c l r L . 



Here the symbol ^ indicates the vector difference 

 between the two quantities and not the simple algebraic 

 difference. It must be remembered that the applied 

 voltage will not be in phase with the energy voltage c l r r 

 Thus the voltage induced in the secondary winding is 



(e, ~ c r ) x ? 



The voltage at the terminals of the secondary will only 

 have this value when the secondary current is zero. When 

 a current flows in the secondary, there will be a loss of voltage 

 due to the resistance of the windings, and consequently 

 the secondary voltage 



ffl / /77 



* 8 'I 2 



1 ~W~ "* l c l *"l 7FT ~t~ 2 ^ 

 - 1 1 \ -i i 



= e. 



But -" or c- 



. T n T, 



ft, = e - <* c, ~ r^-- + c, r, 



T.- 



T 

 or putting / = k, the ratio of the windings, 



