 Since charge continues to arrive at the end of the line through the incident current, but no current is leaving the line, then conservation of electric charge requires that there must be an equal and opposite current into the end of the line.Essentially, this is Kirchhoff's current law in operation.This equal and opposite current is the reflected current, formula_14, and since

there must also be a reflected voltage, formula_16, to drive the reflected current down the line.