58 STATIC ELECTRICITY 



As another illustration, suppose we have two inflated spheres 

 charged with equal + 5 and - 5 respectively and near together, 

 so that nearly all the lines of strain go from one to the other. 

 Let us further suppose that we have two plates charged with H 

 and - 5, and with five lines of strain between them, as in Fig. 4 



Let us suppose that in the spheres the -f charge is below am 

 in the plates the + charge is above. Then the lines of strain a 



\x 



Fio. 48. 



in opposite directions, as indicated by the arrow >. Now mo\e the 

 two spheres towards and finally into tin ip the plate*. 



When the nearest lines of strain of the two systems come togvtlu i 

 the strains are in opposite directions, and where ti. 

 will neutralise each other and disappear, and ur ma\ trier tin- 

 successive steps in what happens to OIK- line of -train some* hat 

 as in Fig, 49. Repeating thi> process, we may imagine that in this 

 way, say three out of the five line- of -train between the spheret 



FIG. 49. 



are neutralised one after the other, and that ultimately \\e 1 

 the arrangement shown in Fig. 50. We still have five lines from 

 each sphere, but three come to the upper from the top plate, and 

 three go from the lower to the bottom plate, and only two go 

 between the spheres. 



Molecular hypothesis of electric strain. 1 1 may be u >e f 1 1 1 

 to give here a hypothetical representation of the condition of a 

 dielectric when it is the seat of electric strain. We IM^UI 1\ 

 assuming that the molecules of the dielectric are really made up 



