1'2- EFFECT OF CAPACITY. 



motive force produced by each was partly or entirely 

 neutralised by the other. Thus, for the particular case, 



ft 



whenZirnLc = - '^ the resultant idle electromotive 



2 TTTl K 



force is zero, and the combination offers no opposition 

 to the changes of the alternating current. 



When the capacity and self-induction are in parallel, 

 the electromotive force at their common terminals depends 

 only upon the voltage of the supply, and is clearly inde- 

 pendent of the nature of the two branch circuits. It is, 

 however, possible for the inductance and capacity to have 

 a combined effect on the current in the external circuit, 

 for there may be a lagging current produced in the branch 

 containing self-induction which may partially or entirely 

 neutralise the leading current flowing in the branch con- 

 taining capacity as regards the external circuit. 



^c 



FIG. 57. CONDENSER AND INDUCTANCE IN PARALLEL. 



Suppose, for instance, that an inductive resistance r 

 with an inductance L henries, and a condenser C with 

 capacity K farads, are connected in parallel, as shown 

 in Fig. 57. 



s* 



If 2 TT n L c - = the lagging current flow- 

 2 w n 1\. 



ing from T l to T 2 (Fig. 57) through the branch r 



y 



will be equal to -~ = if the resistance of the circuit 

 , Z ir 71 Li 



is negligible, and this will be equal to the leading 

 current 2 * n K V flowing through the branch C. 

 The total current flowing from T l to T z is thus 

 zero so far as the external circuit is concerned, 

 since the currents in the two branches are always 

 simultaneously equal and opposite in phase, although 

 a circulating current will flow in alternate directions 

 round the circuit 1\C r l\ r. It will thus appear that 

 whatever voltage may be applied between the terminals 



