... for example, inthree of the four quadrants of the i-v characteristic and can therefore act as sources of energy for specific combinations of voltages and currents. An example of thisdual behavior ... amount of resistance, the magnitude of which depends onPart I Circuits 31the electrical properties of the material. Resistance to the flow of current maybe undesired—for example, in the case of ... terminals of a circuit elementdefines the behavior of that element within the circuit. In this section we shallintroduce a graphical means of representing the terminal characteristics of circuitelements....