DIELECTRIC SPHERE IN A UNIFORM FIELD. 



147 



163. The flow of force from the sphere is equal to the flow 

 which traverses it, va 2 (< + F^) increased by the flow - 3?r0 2 F { , which 

 corresponds to each of the surface layers. 



We have therefore 



Q = 



1 + 2 



The equivalent circle of flow on the original equipotential surfaces 

 would have a radius determined by the equation 



!=9/r2 



Fig. 43- 



so long as ft > i this radius is always greater than that of the sphere. 

 The force in the interior is 



it is equal to - < if /x = 2, which is approximately the case with most 



4 3< 



dielectrics, and becomes equal to when ft, is very large. 



L 2 



