DURATION OF THE RELATIVE PROPAGATION. 



219 



The curve A (Fig. 56) represents the values of the ratio of the 



V a?x 2 

 potentials , as a function of /, by taking a = = z 2 t. The 



VG 4 



ordinate remains zero for some time near the origin, and only com- 

 mences to acquire an appreciable value from the period in which 



& 



/ = -. The asymptote to the curve is parallel to the /-axis at a 



4 

 distance from this axis equal to unity. 



0,5 



\ 



\ 



\ 



\ 



\ 



TV 



\ 



sin 



O.I 



Fig. 56. 



228. The expression for the current at the distance x, is 



__ _oi_ _ 



L " ~ j o 



p dz ' ttor p JIT 2 Jt ' 



replacing z 2 by - , we get 



(7) 



T "0 / " 



=A/ 7 



