﻿1G4 Effect of Electricity on Streams of Water Drops. 



We may now recall for electrified streams the experimental 

 facts which require explanation : — 



1. The alignment of all electrified streams for a certain 

 distance beyond the inductor ;, 



2. The coalescence of the drops for smaller voltages on the 

 nductor ; and 



3. The mutual repulsion of the drops at higher voltages. 



(1) Alignment. 



Two elements enter in to cause this alignment. In a 

 succession of drops, such as in figs. 2 and 9 b, it is likely 

 that the forces of attraction between the neighbouring drops 

 are sufficient to carry them along identically the same path. 

 Acain, as is shown by the influence of vibrating bodies on 

 the breaking stream, if the drops are sent off under initially 

 the same conditions they will travel over the same course. 

 Now just as the drops form they will be under the strong- 

 attraction of those just leaving, and, also, just as they break 

 from the main continuous column they will be strongly 

 attracted to it by the force deducible from equation (11) ; if 

 any drop then has initially a tendency to diverge from the 

 general path it will be pulled back. Consequently all the 

 drops will be given their velocities in the same initial direction. 



(2) Coalescence. 



Keeping in mind these electrostatic forces, no difficulty 

 should be found in the explanation of coalescence. When 

 two drops bearing unequal charges, or two unequal drops 

 bearing equal charges, are brought closely enough together 

 there are immensely strong, increasing forces of attraction 

 between them and coalescence will surely take place if the 

 resulting drop is not too large to be unstable. One would 

 expect that at the moment of collision there would be an 

 electric discharge between the two adjacent spheres. Many 

 influences conspire to bring the drops in the stream closer 

 and closer together. If in a stream the velocity of the drops 

 is sufficient to carry them a vertical distance of 10 cm., two 

 drops breaking away 1/1000 of a second apart will be distant 

 from one another approximately 'II cm. at the beginning 

 of their journey. When the first one has reached the top of 

 its course, taking into consideration only gravity, the distance 

 between the drops will be approximately 5xl0" 4 cm. 

 Again the friction of the air for a given velocity will cause 

 a greater retardation in the case of small drops than in the 

 case of large ones, which will tend to bring a large drop 

 nearer to the smaller one ahead of it. 



