Potential difference is the same across every parallel branch. Current splits at junctions and the branch currents add to the total current. Adding another resistive branch provides another path, increasing total current and reducing total resistance at fixed supply p.d. Example: Predict total resistance when an extra branch is added. It decreases; the supply provides more total current at the same p.d. A correct answer needs an appropriate unit as well as a numerical value. Justify your answer.