62 Dr. McLachlan on Effective Inductance, Effective 



From /=2000— to /= 10,000 — the value of L el /L e2 

 remains approximately constant. (See Table I.) Since 

 Ci/C 2 is constant, it follows that u is constant. We will 

 also assume that k 2 is constant. For a certain B.T.-H. 

 inductor type magneto we have 



C 2 = 55 picofarads (including leads). 

 d = 0*18 microfarad. 



u = 0*7. 



Taking s as unity, the following values of n 2 /ni are found 

 for different values of k 2 (see Table III.). 





Table III. 



W2/W1. 



h\ 



5-0 



0-84 



4-3 



0-8 



3-4 



0-7 



It is very probable, judging from the experiments of 

 Taylor- Jones, that the value of k 2 lies between 0'7 and 0*84. 

 Assuming its value to be 0'8, the foregoing expression can 

 be utilized to calculate 0. Thus we find that sm<£ = 0'93, 

 and from (11) the value of U is 1. In order to obtain V 2 

 we must substitute in (10). The individual magnitudes 

 of >?! and n 2 not being known, a difficulty arises with regard to 

 the values to be assigned to L el and L e2 , since both of the latter 

 vary with the frequencies rii and ?i 2 . As a first approxi- 

 mation we will take the values of L el and L e2 at a frequency 

 of 6000^- per second. This gives L el = 3'14 x 10~ 3 henry 

 and L e2 =14"4 henries. Substituting the above values in 

 (10) we find that the peak voltage in the absence of loss 

 is V 2 = 12,600 volts for a current of 2 amperes. With 

 2 amperes broken in the primary at full advance, the peak 

 voltage was about 10,000. Thus due to the losses, (a) the 

 reduction in peak voltage is 21 per cent., {b) the loss in 

 energy is 60 per cent, of the actual energy given by 

 iU 2 V2 2 = 2*8 x 10" 3 joule. The reduction in* peak voltage 

 found from the calculation in the preceding section worked 

 out at 33 per cent., and the loss was 110 per cent, of iC 2 V 2 2 . 



Consider the conversion of the electromagnetic energy 

 in the primary winding into electrostatic energy in the 

 secondary. Apart from the loss which occurs in both 

 circuits, we must take the coupling and other factors into 

 account. In a magneto or an induction-coil with a primary 



