﻿Effective Adjustment of an Induction-coil, 



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electrostatic form in the secondary circuit, and the se condary 

 potential must in these circumstances have its greatest 

 possible value for a given initial energy-supply Jl^y. 



It was shown in the previous paper to which reference 

 has been made * that the value of this maximum secondary 

 potential, still on the assumption that the resistances are 

 negligible, is 



k 



. /L 21 /Lj 



(3/,) 



The energy equation is therefore 



it, ; 2_in v : 



Lio 



'l'o 



2^2' 2m 



The factor L 12 /L 21 arises from the manner in which the 

 capacity 2 of the secondary circuit is denned. It is the 

 charge on one-half of the secondary coil (and the bodies 

 connected to its terminal), divided by the difference of 

 potential of the terminals. The charge on this portion of 

 the secondary circuit is C 2 V 2m , but as some of this charge is 

 at a low er potential than that of the terminals, the eneroy 

 must be less than \C^l m . The correcting factor is L 12 /L 2l . 



There are many values of h and Jj 1 Q 1 I1j 2 Q 2 which satisfy 

 the above conditions. The first four, probably the only ones 

 having any practical importance, are given in Table I. 





Table I. 





%/%. 



*. 



^-l-F 



LA ^ • 



3 



•756 



•429 



7 



•914 



•164 



11 



•950 



•098 



15 



I 



•965 



•070 



If we define the efficiency of an induction-coil as the ratio 



of the maximum electrostatic energy in the secondary to the 



electrokinetic energy in the primary circuit just before the 



interruption of the current («. e., ^L^V 2 ), then the efficiency 



* L. c. pp. 581,584. 



B 2 



