THE LOCALISATION OF BREAKS AND FAULTS. 



481 



<;harges received by each have been equal they will mix and 

 neutralise, and the galvanometer will show no deflection on 

 closing the key connected to it. If any deflection is noticed 

 the slide contacts are shifted until a point is found at which the 



Earth 

 Fig. 264.— Kelvin's Mixed Charge Test. 



•condenser and cable receive equal charges, as proved by their 

 completely neutralising each other and leaving no residual 

 charge to affect the galvanometer. 



The potentials are distributed as in Fig. 26-5. The cable is 



.'lE-e 



I ^' 



I ^ 



EarLh 

 _1_ 



ryw4 



. Earth . 



tj 



Cable (Capacity F) End free 



Condenser 

 {Capacity f) 



HIIII 



Tig. 265. — Distribution of Potentials in Kelvin's ^Mixed Charge Test. 



charged by the diff'drence of potential e and the condenser by 

 E - e in the opposite direction. The capacity of the cable being 

 generally much greater than that of the condenser, the poten- 

 tial necessary to charge both with the same quantity is much 



II 



