Define electromotive force (e.m.f.) as the electrical work done by a source in moving a unit charge around a complete circuit

Understand that electric circuits transfer energy from a source of electrical energy, such as an electrical cell or mains supply, to the circuit components and then into the surroundings

Define power as work done per unit time and also as energy transferred per unit time; recall and use the equations (a) P = W/t (b) P = ΔE/t