ELECTRIC OSCILLATIONS AND ELECTRIC WAVES. 239 



the voltage is again everywhere zero. These reversed currents 

 then begin to produce reversed charges in the regions Ni, and 

 after another quarter of a cycle these currents are reduced to 

 zero and the voltage distribution over the line is represented by 

 the ordinates of the curve 013. The electric field distribution 

 corresponding to the curve 013 then establishes currents in the 

 line and these currents grow to maximum values thus bringing 

 the line back to initial condition ABA'B' after one complete 

 oscillation. 



The actual distributions of current and magnetic field at the 

 instants represented by curves ii and iq are shown in Figs. 175 

 and 177; and the actual distributions of electric charge and elec- 

 tric field at the instants represented by curves 05 and 013 are 

 shown in Figs. 176 and 178. 



voltage node voltage antinode 



voltage distribution (fundamental mode) open 



current antinode current node 



closed current distribution (fundamental mode) open 



Fig. 179. 



The portions of dotted sine curves in Fig. 179 show the current 

 and voltage distributions over a transmission line, open at the 

 distant end, when the line is oscillating in its fundamental mode 

 (lowest frequency) , the oscillations being set up by the alternator 

 A of the proper frequency. When the current is everywhere 

 zero, the voltages across the line are represented by the ordinates 



