S12 
IOWA ACADEMY OP SCIENCE 
will increase uniformly as the capacity is increased. The total 
current will, however, decrease at first, pass through a minimum 
value and then steadily increase. This is a standard procedure 
in the study of current resonance and figure ^17 represents the 
results that would he obtained by plotting such a series of ob- 
servations:. 
Figure 18 is a vector diagram of the currents assuming zero 
phase difference in the condensers. If the impressed electro- 
motive force be taken as the axis of reference the vector OL 
represents the current in the coil which lags by the angle 
r 
given by the relation Cos = — in which expression r is the 
z 
resistance of the coil and z its impedance. The veetors 
OC 2 , etc., represent different , values of the current in the con- 
densers, and the vectors OB^y etc., are the corresponding 
resultant or total currents as found by the parallelogram meth- 
od. The values of the total current obtained by this graphic 
method are represented in figure 17 by the dotted line. It should, 
