PE1RCE. — ESTABLISHMENT OF CURRENT IN COIL. 



165 



We may now determine the march of the current in the primary 

 and the secondary coils of the transformer, for the given values of 

 Ei, n h n 2 , n, and r 2 . Substituting in equations (21), and (22) we get. 



ii = 



T+ 10 4 

 1100 ' 



10 3 



«2 = 



1100 



(13> 



for any given T. Table VIII, columns five and six, contain values of 

 ii, and i 2 corresponding to the value of T which is given in the first 

 column. Figure 10: the curve PRH shows graphically the march of 



Figure 9. The ordinates of boundary of the shaded area represent 

 10* £2 (T)/5, E = 10, m = 100, n 2 = 1000, r, = 1, and r 2 = 10, the abscissas 

 correspond to 100T. The curve OLP shows the manner of growth of the 

 excitation in the core of the transformer (DN), as a function of the time. 



the current in the primary coil; and the curve SEC, bounding the 

 shaded area at the bottom of the figure, the manner of decay of the 

 current i 2 in the secondary. It will be seen from the figure that i\, 

 the current in the primary, builds up very rapidly at the start, but 

 before reaching its maximum value it remains for a comparatively 

 long time almost exactly parallel to the time axis. During this time 

 the indication of an amperemeter in the circuit does not change per- 

 ceptibly, and yet the flux of magnetic induction through the core is 

 increasing at a very nearly constant rate. The shaded area, bounded 

 by the curve PRH and its asymptote KD, which is a measure of the 



