What is the electromotive force (emf) of a cell defined as?

The electromotive force (emf) of a cell is defined as the cell potential when balanced by an opposing potential. This definition emphasizes that emf represents the maximum potential difference that the cell can produce. It reflects the capability of the cell to perform work, driving the movement of electrons through an external circuit.

In practice, when the cell is connected to a load or an external circuit, the emf indicates how much voltage is available to overcome any internal resistance and external loads. It is essentially the inherent tendency of the electrochemical reactions occurring in the cell to drive the flow of electrons, and it remains constant until the cell equilibrates with an opposing potential.

Other choices might include elements relevant to electrochemical cells, but they do not accurately describe what emf represents. For example, the maximum current produced (first option) is dependent on the load and resistance in the circuit, not a direct measure of the cell’s inherent power. The sum of all individual potentials (third option) could misrepresent the cell behavior since emf is specifically about the potential difference across the entire electrochemical system rather than individual contributions. The voltage drop across the anode (fourth option) only considers one half of the electrochemical reaction and does not provide a full picture of the