Introduction

Electromotive force (emf) is the characteristic of any energy source capable of driving electric charge around a circuit; despite its name, an emf is not literally a force at all, but rather the work done in moving a unit of electric charge once around the complete circuit, measured (like potential difference) in J/C, i.e. volts. Various physical sources can supply an emf -- electrochemical cells, thermoelectric devices, solar cells, and electrical generators among them -- and of these, electrical generators are by far the most powerful, used for essentially all large-scale electric power generation. This section focuses specifically on how an emf can be generated through the phenomenon of electromagnetic induction, by changing the magnetic flux linked with …