PHASE DIFFERENCE OF CONDENSERS 
811 
A RESONANCE METHOD FOR MEASURINO THE PHASE 
DIFFERENCE OF CONDENSERS. 
H. L. DODGE. 
It is a well known fact that when an alternating electromo- 
tive force is impressed upon a condenser the resulting current 
does not lead the electromotive force by the theoretical ninety 
degrees. This is particularly noticeable in the case of paper 
condensers of the telephone type so often used in laboratories 
for the study of the alternating current circuit. When an at- 
tempt is made to interpret such experiments by graphic meth- 
ods it is sometimes found that the power factor of the con- 
densers is so great that it must be taken into account. The 
power factor angle or the angle by which the current lags be- 
hind the theoretical ninety degree lead is known as the phase 
difference of the condenser.^ 
This paper is devoted to a description of a method by which 
the phase difference of paper condensers can be determined 
from the same data that are obtained in an experimental study 
of the phenomena of current resonance. 
Pig. 16. — Diagram showing circuit for determining phase differences. 
Figure 16 represents the circuit which consists of two parallel 
brancheSj one containing a coil with inductance L and resistance 
r, the other a variable condenser C. An alternating electromo- 
tive force is impressed upon this circuit and the value of the 
three currents It* I l, I Ci ^ead as the capacity of the condenser 
is increased by equal steps. The current in the inductive branch 
will remain constant. In the condensive branch the current 
ip. W. Grover, Bureau of Standards, Bull., vol. 7, 495, 1911 ; voL 8, 371, 
1907. These papers contain a very complete discussion of condensers and 
their properties, with numerous references to other work upon this subject. 
