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electromotive force

electromotive force, abbr. emf, difference in electric potential, or voltage, between the terminals of a source of electricity, e.g., a battery from which no current is being drawn. When current is drawn, the potential difference drops below the emf value. Electromotive force is usually measured in volts.

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electromotive force

electromotive force (emf) Potential difference between the terminals in a source of electric current, measured in volts. It equals the energy liberated when this voltage drives the current round an electric circuit. See also electricity

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Electromotive Force

Electromotive Force

In an electric circuit, electromotive force is the work done by a source on an electrical charge. Because it is not really a force but a quantity of energy, the term is actually a misnomer. Electromotive force is more commonly referred to by the initials EMF. EMF is sometimes used as a synonym for electrical potential, or the difference in charge across a battery or voltage source. For a circuit with no current flowing, the potential difference is called EMF. However, electrical potential is not synonymous with EMF; the former refers only to the work done on a unit of electrical charge moving against an electric field, whereas EMF may include non-magnetic, chemical, and other types of work on the charge.

Electrical sources that convert energy from another form are called seats of EMF. In the case of a complete circuit, such a source performs work on electrical charges, pushing them around the circuit. At the seat of EMF, charges are moved from low electrical potential to higher electrical potential.

Water flowing downhill in a flume is a good analogy for charges in an electric circuit. The water starts at the top of the hill with a certain amount of potential energy, just as charges in a circuit start with high electrical potential at the battery. As the water begins to flow downhill, its potential energy drops, just as the electrical potential of charges drops as they travels through the circuit. At the bottom of the hill, the potential energy is minimum, and work must be performed to pump it to the top of the hill to travel through the flume again. Similarly, in an electrical circuit, the seat of EMF performs work on the charges to bring them to a higher potential after their trip through the circuit.

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Electromotive Force

Electromotive force

In an electric circuit , electromotive force is the work done by a source on an electrical charge. Because it is not really a force, the term is actually a misnomer; it is more commonly referred to by the initials EMF. EMF is another term for electrical potential, or the difference in charge across a battery or voltage source. For a circuit with no current flowing, the potential difference is called EMF.

Electrical sources that convert energy from another form are called seats of EMF. In the case of a complete circuit, such a source performs work on electrical charges, pushing them around the circuit. At the seat of EMF, charges are moved from low electrical potential to higher electrical potential.

Water flowing downhill in a flume is a good analogy for charges in an electric circuit. The water starts at the top of the hill with a certain amount of potential energy, just as charges in a circuit start with high electrical potential at the battery. As the water begins to flow downhill, its potential energy drops, just as the electrical potential of charges drops as they travels through the circuit. At the bottom of the hill, the potential energy is minimum, and work must be performed to pump it to the top of the hill to travel through the flume again. Similarly, in an electrical circuit, the seat of EMF performs work on the charges to bring them to a higher potential after their trip through the circuit.

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