Difference Between EMF and Potential Difference (With Table)

EMF (electromotive force) and potential difference, both terms are physics terms and are consequently associated with electric potential. The EMF is the potential difference when the circuit is open, and no current is flowing through the external circuit. While the potential difference is measured when the current is flowing across the terminals of the battery. Although both of these terms are measured in volt, they do have some differences.

EMF vs Potential Difference

The difference between EMF and the potential difference is that electromotive force (EMF) is the potential difference between two terminals of the battery when there is no current flow in the circuit. It is the amount of energy that is provided by the battery itself to each coulomb of charge. On the contrary, Potential difference is the difference in the amount of energy released or required in the transmission of a unit of electricity from one point of the terminal to another.

Emf refers to electromotive force, which is the energy supplied or provided to the unit charge by the battery or cell. In other words, it is the potential difference between the two terminals of the battery or cell when the circuit is open, or no current is drawn off from the cell.

Potential difference is the amount of work done between two terminals of the cell in moving a unit charge from one point to another. It is the difference of electric potential between two points in a close circuit in which current is flowing.

Comparison Table Between EMF and Potential Difference

Parameters of ComparisonEMFPotential Difference
DefinitionElectromotive force (EMF) is the potential difference between two terminals of the cell when the circuit is open or no current is flowing in the external circuitPotential difference is the difference in electric potential between any two points in the closed-circuit or when current is flowing
Resistance BehaviorEMF does not depend on the resistance of the circuitIt depends and is directly related to the resistance between the two points
Voltage MagnitudeIt is the maximum voltage that can be drawn or achieved from the cellIt is always less than the maximum voltage that one can obtain from the electric cell
RepresentationEMF is represented by letter EPotential difference is represented by letter V
FormulaIt is mathematically presented by E = I (R+r), where R+r is the total resistance(External and internal) It is mathematically presented by V = E – Ir, where R is the total external resistance
Electrical EnergyIt identifies and determines the gain in electrical energy by electrons in the circuitIt determine the loss in the electrical energy by electrons as they flow in the circuit

What is EMF?

Electromotive force (EMF) is the energy that is supplied to the individual charge unit by the cell. For instance, when an electrical energy source is connected across R resistance, then consequently it maintains a steady current. The battery connected is responsible for positive charge flow in the external circuit.

EMF is simply the energy or work required for the transmission of positive charge from the negative terminal to the positive terminal of the battery when the circuit is open or no current is flowing in the external circuit initially. It is measured in volt and presented by the letter E. Mathematical formula of EMF is E = I(R+r), where R+r is the total resistance (external and internal) of the electric circuit.

What is Potential Difference?

Represented by the letter the V, the potential difference is the work done or performed in the transmission of a unit charge from the negative terminal to the positive terminal when the circuit is closed, or the current is flowing in the electric circuit. While moving a charge from one point to another, energy is released in the form of heat.

The potential difference is measured in volt and mathematically expressed as V = E – Ir, where r is the internal resistance of the battery. The major highlight to remember is that electromotive force is simply the driving force or the cause, while the potential difference on the other side is the result of electromotive force. The potential difference depends on the condition of the electric circuit. It does not remain constant.

Main Differences Between EMF and Potential Difference

  1. EMF and potential difference, both terms are quite the same as they determine the electric potential. Electromotive force (EMF) is the potential difference between two terminals of the cell when the circuit is open, or no current is flowing in the external circuit. The potential difference, on the other side, is the difference in electric potential between any two points in the closed circuit or when the current is flowing.
  2. Resistance plays an important role in determining various values in the electric circuit. Although EMF does not depend on the resistance of the circuit. But potential difference depends and is directly related to the resistance between the two points.
  3. In physics, terms are presented with a symbol. In the same way, EMF and potential differences are also represented by using a symbol or letter. EMF is represented by using the letter E. On the contrary, the potential difference is represented by using V.
  4. EMF and potential differences both are related to electric circuits and potential. Both of these terms have a mathematical formula for convenient and accurate calculation. EMF is mathematically presented by E = I (R+r), where R+r is the total resistance(External and internal). While the potential difference is mathematically presented by V = E – Ir, where R is the total external resistance.
  5. While working on an electric circuit, there is essential loss and gain of energy. EMF identifies and determines the gain in electrical energy by electrons in the circuit. On the contrary, potential differences determine the loss in the electrical energy by electrons as they flow in the circuit.

Conclusion

EMF and potential difference both terms have their significances. Potential difference is a wide and comprehensive term used in electric and magnetic fields. However, the electromotive force is majorly and solely used in the concept of the electric circuit. In the electric circuit, EMF is simply the driving force, and the potential difference is the result of EMF.

References

  1. https://aapt.scitation.org/doi/abs/10.1119/1.13226
  2. https://pubs.acs.org/doi/pdf/10.1021/j150300a003

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