THE ELECTRIC ARC 



from that which had previously been flowing through 

 the arc. 



A larger potential difference will be needed to force this 

 smaller current through the arc, as may be seen from 

 Fig. 54 which gives diagrammatically the relation between 



C CURRENT 



FIG. 54. 



the potential difference and the current of the arc. Thus 

 let Ob represent the sum of the currents flowing to the arc 

 and the condenser. Let ab represent the current flowing 

 into the condenser at some given moment. Oa will then 

 be the current flowing through the arc. W is the potential 

 difference at the terminals of the arc when no current is 

 flowing to the condenser, and the larger quantity, aa', is 

 the potential difference when part of this current is flow- 

 ing to the condenser. 



There will, however, be a limit to the increase in the 

 voltage which can be supplied to the arc and when this is 



