Method of Measuring Energy dissipated in Condensers. 21 



where t is the period of the fundamental component of the 

 impressed electromotive force and the capacity of the 

 condenser. 



There is another practical advantage resulting from this 

 arrangement, namely, that the resulting resonance raises the 

 electromotive force at the terminals of the condenser very 

 greatly, saving the necessity of raising the voltage by trans- 

 formers. And a third advantage now appears in the fact that 

 the wattmeter may be inserted across the low-voltage supply 

 wires to measure the total power expended upon coil and 

 condenser. Then subtracting the IV loss of the coil, the 

 remainder will be the power expended upon the condenser. 

 This supposes, of course, that there is no iron core and no 

 eddy-current loss in the copper coil itself. 



The Resonance Method, 



Fig. 1 shows the connexions for this method with the coil 

 in series with the condenser. M, N are the low-voltage 

 supply-wires of an alternating circuit, S is an adjustable re- 

 sistance, E is a dynamometer, F a wattmeter, R a non- 

 inductive resistance in shunt with the coil and condenser, 



Fig. 1. 



N 



Dyn. 





R 









"W 









r * 





p ■ 











lltht 



1 B 







V V V 







\XXUJ 







Coil 



Condenser 



joining the points A and D. The wattmeter therefore mea- 

 sures the power expended between the points A and D, 

 including the Vr w loss in the fixed coil of the wattmeter, but 

 not including the i 2 J& loss in the shunt-resistance R. The 



13U5 



