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Electromotive force (EMF) - High School Physics Tutorial

Electromotive force (EMF)

Electromotive force (EMF) also called Voltage sometimes is the measure energy which causes the flow of current through a circuit or conductor. By definition:

Electromotive Force is the energy per unit charge causing the charge to move through the circuit.


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By the name Electromotive force might sound like a force ; But EMF is not exactly a force instead it is the measure of Energy or Work done per charge which causes the charge to move around in a circuit as shown in the figure below: 
What is Potential Difference?

Electric potential is the electric potential energy which tends to move the charge through the circuit and the potential difference (PD) is the difference between the electric potential of two points in a circuit. In any circuit Potential difference between two points is almost equal to the Electromotive force between them , and thee measure of PD is almost same as that of EMF also the both have same units i.e. Volt.


Mathematics on EMF:

Mathematically EMF is the measure of work done per charge to move the charge. So the formula for 


EMF is:

Where E = Electromotive force W = Work done by the current flowing through a circuit and Q = total charge flowing through the circuit.

Thus Electromotive force is the derivative of Work Done by the current with respect to the charge flowing.

The Unit of EMF is: Joules per Charge. Which is usually denoted by Volt or “V’.

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