﻿THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIE 



[SIXTH SERIE 



JANUARY 191 



I. On the most Effective Adjustment of an Induction-coil, 

 By E. Taylor Jones, D.Sc, Professor of Physics in the 

 University College of North Wales, Bangor*. 



[Plate I.] 



IN a recent paper t it was shown that the secondary 

 potential and spark-length developed by an induction- 

 coil, when a given current is interrupted in the primary 

 circuit, are greatest under the following conditions : — 



(1) The ratio njn x of the two frequencies of elec- 

 trical oscillation of the system has one of the values 

 3, 7, 11, ..... ; 



(2) L 1 1 =(l-^)L 2 G 2 t. 



The first is the condition that maxima of the two potential 

 waves in the secondary circuit should occur simultaneously, 

 the second that the sum of the amplitudes of the two waves 

 should be a maximum for a given value of k. 



It was further stated that the most effective of the ratios 

 specified in (1) is ^2/^ = 3, and that in this case the 

 conditions are satisfied by the adjustment /• == '756, 

 LA = '429 L 2 C 2 . 



* Communicated by the Author, 

 t Phil. Mag. xxvii. pn. 580-586, April 1914, 



% L T , L 2 are the self-inductances, C v C, the capacities, and k is the 

 coupling coefficient of the primary and secondary circuits. 



PUl Maq. S. 6. Vol. 29. No. 169. Jan. 1915. B 



