- The Electromotive Force (EMF) is the name given to the Potential Difference (Voltage) of the power source in a circuit
- The Electromotive Force (EMF) is measured in Volts (V)
The EMF is the voltage supplied by a power supply: 12 V in the above case
- The EMF of a power supply (measured in volts, V) is the amount of energy (measured in joules, J) supplied to each coulomb of charge passing through that power supply
Think of the EMF as being the energy per coulomb.