44 



ELEMENTS OF STATIC ELECTRICITY. 



enough to produce divergence, as at J., Fig. 5, and, while 

 in that position, the disc be touched with the finger, as 

 at B, the leaves will converge, and remain so as long 

 as the electrified body is held near ; but on its removal 

 as at (7, they will diverge, and remain divergent, the 

 same as after contact of the electrified body with the 

 disc. 



Fig. 5 Induction Illustrated. 



Here, then, is electrification by induction, without 

 any transfer of electricity by contact. How can this be 

 accounted for ? 



When the electrified body is brought near, whether 

 its charge be positive or negative, the effect of induction 

 is to produce a temporary change. of the potential of 

 the electroscope, and the leaves diverge. 



If the charge of the electrified body be positive, elec- 

 tricity is repelled from the disc to the leaves, and they 

 diverge, being positively electrified to the same poten- 

 tial, and hence mutually repellent, and also attracted 

 by the lower potential of surrounding bodies. 



But if the electrified body be negatively charged, 



