what is emf in physics

Electromotive force (EMF) is a term used in physics to describe the energy transfer to an electric circuit per unit of charge. It is the electric potential produced by either an electrochemical cell or by changing the magnetic field. EMF is measured in volts and is represented by the symbol E. EMF is not a force, but rather a potential difference between two points in a circuit/Book%3A_University_Physics_II_-Thermodynamics_Electricity_and_Magnetism(OpenStax)/10%3A_Direct-Current_Circuits/10.02%3A_Electromotive_Force). It is equal to the work done on the charge per unit charge when there is no current flowing/Book%3A_University_Physics_II_-Thermodynamics_Electricity_and_Magnetism(OpenStax)/10%3A_Direct-Current_Circuits/10.02%3A_Electromotive_Force). EMF is independent of circuit resistance, while potential difference depends on the resistance between the two points during the measurement. EMF is the maximum potential difference that is delivered by the battery when there is no flow of current, while terminal voltage is the potential difference across the terminals of a load when the circuit is on. An EMF source acts as a charge pump, moving negative charges from the positive terminal to the negative terminal to maintain the potential difference/Book%3A_University_Physics_II_-Thermodynamics_Electricity_and_Magnetism(OpenStax)/10%3A_Direct-Current_Circuits/10.02%3A_Electromotive_Force). EMF is important in renewable energy research topics, as it is generated from solar cells.