Series and parallel circuits — Recall

State the rules relating (a) currents at a junction in a parallel circuit, (b) p.d.s in a series circuit, and (c) p.d.s across parallel branches.

(a) The sum of the currents entering a junction equals the sum of the currents leaving it. (b) The total p.d. across the components in a series circuit equals the sum of the individual p.d.s across each component. (c) The p.d. across an arrangement of parallel resistors is the same as the p.d. across each individual branch of that arrangement.