 There are several approaches to understanding reflections, but the relationship of reflections to the conservation laws is particularly enlightening.A simple example is a step voltage, formula_1 (where formula_2 is the height of the step and formula_3 is the unit step function with time formula_4), applied to one end of a lossless line, and consider what happens when the line is terminated in various ways.The step will be propagated down the line according to the telegrapher's equation at some velocity formula_5 and the incident voltage, formula_6, at some point formula_7 on the line is given by

The incident current, formula_9, can be found by dividing by the characteristic impedance, formula_10

The incident wave travelling down the line is not affected in any way by the open circuit at the end of the line.