In what configuration should parallel circuits be evaluated?

Parallel circuits should be evaluated by total current because, in a parallel configuration, the total current flowing through the circuit is the sum of the currents through each parallel branch. Each branch in a parallel circuit has the same voltage across it, which allows for the evaluation of current flow independently within those branches.

In parallel circuits, as voltage remains constant across all components, it's critical to apply Kirchhoff's Current Law, which states that the sum of currents entering a junction must equal the sum of currents leaving that junction. This leads to the understanding that knowing the total current helps assess how the circuit functions under different conditions.

Using total voltage or resistance doesn't provide the direct insight needed for parallel circuits because they don't operate under the same principles as series circuits. In series, the total voltage drops across individual components, while in parallel, the same voltage exists across all paths, highlighting why evaluating by current is essential in understanding how the entire circuit behaves.