ELECTRIC OSCILLATIONS AND ELECTRIC WAVES. 215 



For example, let R = 30, then E r = + E/2, and J r = - 1/2. 

 When R = a/3, then E r = - E/2 and J r = + 7/2. 



Reflection at a place where the line constants L and C 

 change. The doubled arrow in Fig. 151 represents a wave which 



airline ]L= a 



cable 



E 



Fig. 151. 



Showing a rectangular wave pulse partly reflected and partly transmitted at a 

 point where an air line connects with an underground cable. 



has been partly turned back or reflected at a place where an air 

 line connects to an underground cable, and the arrow EJt 

 represents the wave which enters the cable. In this case we have : 



E + E r = E t (14) 



I + Ir = It (15) 



f=+a (16) 



f-- <'7> 



Y t = + b ( l8 ) 



and from these equations we find : 



(20) 



