Power and energy as systemic properties — Part I: Electrical circuits

We examine some aspects of the nature of physical energy and power for electrical circuits. The question raised is how energy is transferred from the environment to a circuit, or between circuits. Does this transfer occur terminal by terminal, or does it happen along a set of terminals? In other words, is the transfer of energy a `local´ or a `global´ phenomenon? The main conclusion drawn from the analysis presented is that power does not propagate along terminals, but along a port, that is, along a set of terminals having the property that the sum of the currents is zero. In other words, energy transfer is a `systemic´ property: it depends on what is happening in a system as a whole. In a companion paper [6] we examine this phenomenon for mechanical systems.