ELECTRIC OSCILLATIONS AND ELECTRIC WAVES. 275 



Note. The battery current starts at a definite value i, as explained in the note 

 to problem 148, and retains this value until the wave of starting travels to the end of 

 the line and back, when the current suddenly increases to the value of 2i and so on. 

 The effect of the resistance of the transmission line is too complicated to permit of its 

 being easily taken into account, and therefore the resistance of the transmission line is 

 assumed to be zero in problems 148, 149, 150 and 151. 



152. A long train of cars has highly elastic springs in the 

 couplers. Describe the precise manner in which the train gains 

 velocity under a constant pull of the locomotive, ignoring friction. 



Note. The manner of starting of the train is precisely analogous to the manner 

 of setting up a current in the transmission line in problem 149. 



