What does the term "electromotive force" (EMF) refer to?

Electromotive force (EMF) is defined as the voltage generated by a source, such as a battery or generator. It essentially represents the energy supplied per unit charge by the source to move electrical charge through a circuit. EMF is the driving force that pushes electrons through a circuit, and it is measured in volts.

This concept is critical in understanding how electrical systems operate because it quantifies the ability of a source to do work on charge carriers. A battery produces EMF due to chemical reactions within it, while a generator generates EMF through mechanical means such as electromagnetic induction. Recognizing the role of EMF helps in grasping other electrical characteristics, such as current and resistance, as outlined in Ohm's law where voltage (voltage and EMF can be discussed interchangeably in certain contexts) equals the product of current and resistance.

The other options refer to different electrical concepts: resistance relates to how much a conductor opposes the flow of current, current is the flow of electrons through a circuit, and power describes the rate at which energy is consumed or converted in a device. Each of these concepts is important but distinct from what EMF represents.