214 ADVANCED ELECTRICITY AND MAGNETISM. 



the end of a line which is connected to a non-inductive circuit of 

 resistance R. The actual current at the end of the line is / -f- I r 

 and this current flows through R so that the voltage across the 



f* f 



<R 



wire 



Fig. 150. 



Showing a rectangular wave pulse partly reflected from the non-inductive 

 receiving circuit of resistance R. 



end of the line (E + E r ) must be equal to R(I + 7 r ). There- 

 fore we have : 



E + E r = R(I + Ir) (9) 



Also we have: 



| = + a (10) 



and 



f=-<* (n) 



where a is written for \j~7,- Solving equations (9), (10) and 

 (n) we get: 



E r = E (^r a ) ( I2 ) 



and 



(a) PF/^ew R = a there w wo reflection at all; the entire wave w 

 swallowed up, as it were, by the circuit R. (b) When R is greater 

 than a there is partial reflection with reversal of current, (c) 

 When R is less than a there is partial reflection with reversal of 

 voltage. 



