The electromotive force (e.m.f.) of a battery is 12.0 V.
What does this mean?
12.0 J12.0\text{ J}12.0 J is the maximum energy the battery can provide in 1.0 s1.0\text{ s}1.0 s.
12.0 J12.0\text{ J}12.0 J is the total electrical energy stored in the battery.
12.0 J12.0\text{ J}12.0 J of energy is provided by the battery to drive a charge of 1.0 C1.0\text{ C}1.0 C around a complete circuit.
12.0 J12.0\text{ J}12.0 J of energy is provided by the battery to drive a current of 1.0 A1.0\text{ A}1.0 A around a complete circuit.
55 exam-style questions on CIE IGCSE Physics 4.2.3a Electromotive force. Each one has a worked solution and a mark scheme showing where the marks go.