Resistance, and Self- Capacity of Magneto Windings. 11 



<CR//2, the value of go 2 increases with the inductance; 

 when L e >OR e 2 /-5 co 2 decreases with increase in inductance. 

 Thus increasing the inductance will increase or decrease o> 

 according as \\ e are at B or A. 



Let L e = effective inductance of primary winding. 

 L = inductance of air-core coil. 

 C = primary capacity. 

 co = pulsatance for primary alone. 

 a>i = pulsatance for primary -f air-core coil. 



Then from (10 J we have 



R e = 2L^ L ^-a> ' 2 )\ (17) 



^ =2 ^ + L )((T^L)C-^) 1 - * * (18) 



Since the values of co and w, are not very different, the 

 values of R e from (17) and (18) are practically identical, 

 provided the max. currents and the damping are equal in 

 both cases *. Hence, equating (17) and (18) and squaring 

 both sides, we obtain 



L Hiu-'^) = ^ LL «+ L2 )((i^c-'4 



from which we get 



-LG) 1 2 ±\LW + U^-Lco ] 2 )(G, i 2 -co 2 )\ i 

 L e =- — r^-r- — • ■ (1») 



In the case mentioned above, the capacity employed 

 in determining the inductance is not stated, but we will 

 assume this to be 1 microfarad. Neglecting the effective 

 resistance as Dr. Campbell did, we have 



o) u 2 = y ~i for the primary winding 

 ij e \j 



= l/(ir23 x 10- 9 ) = 1-61 X 10 +s , 



oi 2 — j= j~ n (£ or primary -fair-core coil) 



= 1-73 Xl0 +8 . 



* The maximum current should (if possible) be such that the 

 inductance, resistance, and periodic time do not vary appreciably as 

 the oscillations die away. 



