130 



Capt. E. V. Appleton on tie Effects of 



extreme exhaustion, but may be positive or negative in a 

 tube possessing an appreciable amount of gas. The quantity 

 k 2 is usually negative and small numerically compared 

 with k-l. As an approximation we may therefore regard the 

 grid circuit inside the tube as possessing a conductance k u 

 which may be either positive or negative. 



In the use of the tube as an amplifier or rectifier of high 

 frequency oscillations, the closed oscillatory circuit of the 

 receiver is connected between the grid and the filament (see 

 fig. 1), and the conductance k x thus acts as a leak to the 

 condenser. 



Fig. 1. 



p, plate ; g, grid; /, filament ; L.T., filament heating battery. 



If y represents the current through the inductance and E 

 the potential difference between the points A and B, we 

 have 



_ E _ L dy_ 

 lJ ~U Rdt> 



y + i=-C 



N dE 



dt ' 



Eliminating y and i we get 



d 2 E , /R , *AdE ;,E „ ^ N n 



the solution of which is oscillatory when 



/R ^f 4 

 U 0/ LC <U ' 



