100 



EFFECT OF CAPACITY. 



When connected to a constant source of electromotive 

 force, no current flows through the condenser. In this case 

 Charge = coulombs =KE. 



During the process of charging, 

 Current flowing to condenser = rate of change of charge. 



When connected to an alternating source of electromotive 

 force the difference of potential between the terminals will 

 change at the same rate as the alternating source. Conse- 

 quently Q = K E will change also. Since current = rate at 

 which quantity flows, the rate of change of K E (measured 

 in coulombs per second) will be numerically equal to the 

 current flowing to the condenser. 



PIG. 44. CURVES OF ELECTROMOTIVE FORCE, CHANGE OF ELECTROMOTIVE FORCE AND 

 CHARGING CURRENT. CAPACITY = 200 MICROFARADS. 



Hence charging current of condenser = capacity x rate 

 of change of voltage at terminals. 



It is now possible to represent graphically the relation 

 between the voltage applied to a condenser and the charging 

 current. 



This is done in Fig. 44, where curve I is a curve of voltage 

 whose maximum value is 25 volts. Curve II. is a curve of 

 rate of change of voltage (measured in volts per radian*), 



* The radian is the unit angle in circular measure, and is equal to about 

 57'3. There are 2 TT radians in a complete circle, or 360. 



