334 PROCEEDINGS OF THE AMERICAN ACADEMY. 



From this equation the values contained in Table V were computed. 



TABLE V. 

 The Voltage-Phase Cycle. 



And from these values three half periods of the voltage-phase cycle are 

 plotted as the sinusoidal curve S of Figure 7. 



The computations when the rectifier is put in place of the 400 ohm 

 resistance can be made only approximately. The differential equation 

 for the current / 2 through the circuit in this case is 



(4) 



Esm o)t — e r = RJ 2 + L 



dl 2 



in which e T is the drop of voltage about the rectifier, E is 5.0 volts, 

 and Ii c the resistance of the deflecting coils = 436 ohms. The drop in 



Figure 7. Rectified cycle computed from the current-voltage values of Figure 5. 



voltage e r about the rectifier is a function of the current. This func- 

 tion is the equation of the current- voltage curve of Figure 5. It is 

 difficult to obtain an exact analytical expression for this function. But 



