We wish to upgrade the wave equations for electromagnetic propagation in lossless and source-free media to account for the possibility of loss. First, let’s be clear on what we mean by “loss.” Specif...We wish to upgrade the wave equations for electromagnetic propagation in lossless and source-free media to account for the possibility of loss. First, let’s be clear on what we mean by “loss.” Specifically, we mean the possibility of conversion of energy from the propagating wave into current, and subsequently to heat. This mechanism is described by Ohm’s law.