Conductors conveying Steady or Transient Currents. 235 

 And the ratio of the two impulses is 



* = §S^ . . . (6) 



Now V-jW + W, where /= ^- (^) 2 . 

 So, noticing that R/R = L/L as nearly as we please, 



p2 = r (M R 4 



The second term is frequently negligible, though there is no 

 difficulty in taking it into account if it is not ; so the ratio of 

 the impulses, at its least, is 



^ _ Si 2 L_ L/^ 



<£'" K 2 'L 'S/K ^ } 



The first of these three numerical factors depends merely 

 on the shape of the acting conductors and their distance 

 apart. The second is a proper fraction which may be made 

 as near unity as we choose. The third involves a comparison 

 between the electromagnetic measure of inductance of the wire 

 included in the circuit, and the electrostatic measure of 

 capacity of the discharged Leyden jar. 



Taking as an example the same round wire conductor as 

 before, with 



K K 



Si= — a> =wz sa y> 



i leg- 



and considering ^- asl -^ \ for inslance, we perceive that 



the two impulses will be equal and just balance each other if 

 the length representing L on the magnetic system of units 

 be 400 times as great as the length representing S on the 

 electrostatic system. Any wire longer than this gives 

 attraction the advantage ; any wire shorter than this favours 

 repulsion. 



Or, with different jars discharging round a given circuit, 

 small jars will exhibit the electrostatic impulse, big ones the 

 electrokinetic. 



Illustrating numerically still further : a length of 30 metres 

 of No. 16 copper wire opened out into a single large loop has 

 a self-induction of 500 " metres " or 50 micro-secohms. Using 

 this as the wire R between the two suspended conductors, 

 the critical-sized Leyden jar which should excite no force 



