210 PROPAGATION OF ELECTRICITY. 



x from P and of l-x, or 7, from P 1? is 



w v-v.i?^;* 



If the point P 1 is on the ground, we have V x = 0, which gives 



e py _ e -y 



(9) V = V ^T^' 



If the wire is unlimited, the constant A is null, and we have 



v=v *-0* 



221. The current in the wire is given by the expression 



VI 1 



~~ P '~d^~ 



if the point P l is connected with the earth, it becomes 



V 

 = 



and, if the wire is unlimited, 



I being the current at the origin of the wire. 



222. RESISTANCE OF A CONDUCTOR WHERE THERE is A Loss 

 BY THE SIDES. From equation (n), the total resistance offered to 

 the electrical current from the point P to the ground, allowing for 

 the branches, is 



