2.1 KIRCHHOFF'S VOLTAGE LAW (KVL)
Consider a DC circuit with many loops as shown in Fig. 2.1-1. Six two-terminal elements are interconnected in this four-node circuit. The interconnection results in seven loops in the circuit. The loops are 1-4-2, 2-5-3, 4-6-5, 1-6-3, 1-4-5-3, 2-4-6-3 and 1-6-5-2. The elements are numbered and the encircled numbers label the nodes.
Two nodes connected by a piece of connecting wire is equivalent to a single node.
The circuit is assumed to be in DC steady-state. That is, all the sources in the circuit are assumed to be constant values and all the circuit variables are assumed to be constants in time.
Thus, there is a steady charge distribution at the terminals and on the surface of each two-terminal element ...