EFFECT OF CAPACITY. Ill 



seen to be a straight line, showing that the current 

 increases in direct proportion to the frequency. 



The curve goes through zero, since with a frequency 

 of the current would become a continuous current, which 

 can only charge the condenser once, and then cease to 

 flow. 



The results may be used to check the accuracy of the 

 formula given previously, viz. : 



0=2*71 KE. 



For the last reading at a speed of 1620, we should 

 have as the value of the current 



O 



0=2*- -p- x -0002 x 100 =-678 amp. 



The actual value observed was '68 amp.* 



The preceding experiments have shown how the 

 capacity and frequency of charge and discharge of a con- 

 denser affect the amount of current in the circuit. 



The quantity of each charge depends not only on the 

 capacity of the condenser, but also on the voltage to which 

 the condenser is charged each time, i.e., on the effective 

 terminal voltage. This is the point to be illustrated in 

 the next experiment. 



EXPERIMENT XX. DETERMINATION OF EFFECT OF 

 TERMINAL VOLTAGE UPON CHARGING CURRENT OF A 

 CONDENSER. 



DIAGRAM OF CONNECTIONS. 



Same as for Experiment XIX., Fig. 50, page 109. 



Instructions. Connect a condenser in series with an 

 ammeter to the source of alternating current. Arrange 

 matters so that the terminal voltage of the condenser can 

 be varied, either by means of a variable resistance in the 

 circuit, as shown in the diagram, or by means of a field- 

 regulating resistance in the generator field circuit. Con- 

 nect a voltmeter to the condenser terminals if the 

 voltmeter is electrostatic, or so as to measure the voltage 



* Again it must be mentioned that such results are only obtainable with 

 an alternator giving sine wave form. With any other wave form we should 

 still obtain a straight line as a result of the experiment, but its inclination 

 would be different, and the current would not be exactly that given by the 

 formula. The formula would only be true of each of the harmonics of which 

 the wave is formed. 



