The EMF (electromotive force) of a cell is the maximum potential difference between two electrodes of a cell. EMF is measure by combining two separate half cells. The \text {E}^ {\varnothing} of individual half cells can also be used to predict overall chemical reactions. Cell Potentials. EMF of a Cell: The maximum potential difference which is present between two electrodes of a cell is defined as the electromotive force of a cell or EMF of a cell. It’s also known as the net voltage between the half-reactions of oxidation and reduction. About. Transcript. EMF is the work done by the cell in moving a coulomb of charge across its terminals. It represents the energy transferred per coulomb to the charges. Some of this energy is lost as heat due to internal energy. Hence the net energy gained by the charge = the emf - heat lost. ay79XI.