By Ian Darney

By invoking the concept of the shift register, a program is developed to simulate the propagation of charges back and forth along a cable. By adding the equations which define the incident, reflected and absorbed currents, a program is developed which can simulate the response of any transmission line to a transient waveform.

The response of an open-circuit line to a 40 ns pulse is simulated and a snapshot is provided of the distribution of current and voltage along the line after an elapsed time of 60 ns. A similar snapshot illustrates the status of a short-circuited line.  

The program itself provides an insight into the mechanism involved. It reveals that voltage and current at any point at any instant are each a function of charge. Further reasoning leads to the conclusion that charge itself is a manifestation of the interaction between photons and conducting material.