Electromotive force (EMF) is a voltage developed by any source of electrical energy such as a battery or photovoltaic cell. The word "force" is somewhat misleading, because EMF is not a force, but rather a "potential" to provide energy. The term EMF is retained because of historical reasons, and is useful to distinguish between voltages that are generated and energy that is lost to resistors.
When a charged particle is present in the EMF, the voltage will supply the particle with kinetic energy which is what drives electric circuits. This energy can then be lost as heat throughout the circuit as the moving current of charges meets electrical resistance. The amount of resistance throughout the circuit dictates how much current will flow in it, given by Ohm's law.
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For Further Reading
For further information please see the related pages below:
- Wikimedia Commons [Online], Available: http://upload.wikimedia.org/wikipedia/commons/8/8d/Duracell_9_Volt_0849.jpg
- Hyperphysics, Electric voltage [Online], Available: http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elevol.html