Cambridge O Level Physics · Syllabus 5054 · Electricity and Magnetism
E.m.f. and potential difference
What is E.m.f. and potential difference?
E.m.f. is the electrical work done by a source in moving a unit charge around a complete circuit, while potential difference is the work done by a unit charge passing through a component; both are measured in volts, and one volt is one joule per coulomb.
This definition is part of the Electricity and Magnetism chapter in Cambridge O Level Physics.
Questions students ask about E.m.f. and potential difference
What is the difference between e.m.f. and potential difference?
E.m.f. is the electrical work a source, such as a cell, does in moving each unit of charge around a complete circuit; potential difference is the work done by each unit of charge as it passes through a component. Both are measured in volts, where \(1\ \mathrm{V} = 1\ \mathrm{J/C}\). E.m.f. describes energy supplied by the source; p.d. describes energy transferred in a component.