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The electromotive force (EMF) and the voltage or potential difference (PD) between the terminals of a battery at a location in an electrical or electronic circuit can be easily confused. Although EMF and possible differences measure volts, the two metrics are quite different.
The electromotive force is caused by converting another form of energy into electrical energy. In potential difference, the electrical energy is converted into other forms of energy. These distinctions can be significant in some electrical and electronic circuit design parts. Therefore, it is important to understand what they are to reduce confusion, and the appropriate terms and terminology can be utilised when necessary.
What is the definition of electromotive force?
The energy per unit charge imparted by an electrical source, such as a battery or an electrical generator, is called electromotive force (EMF). It is an electrical potential generated by an electrochemical cell or a changing magnetic field, not a forced idea. Furthermore, the Faraday law states that the induced EMF is responsible for the growth of the electromagnetic field. On the other hand, the value of EMF remains constant across the course.
What is the meaning of the potential difference between the terminals of a battery?
The voltage difference between two locations in a circuit is the potential difference between the terminals of a battery. It is the transmission of electric energy from one point in a course to another. For example, when current passes through a conductor, the free electrons wander around, resulting in an energy differential across the component and allowing the positive charge to flow in the external circuit. This is known as an electrical potential difference.
Example of electromotive force of the source and potential difference
Take the example of a small battery used to power a circuit to demonstrate the difference between EMF and PD. The voltage will usually be specified on the battery’s exterior package: 1.5 volts for single-cell alkaline cells.
However, it has been discovered that the voltage drops while the battery is in use, especially when heavier loads are applied and as the battery ages and is utilised. Even if the cell or battery is brand new, there will be some voltage loss when it produces electricity. The reason for this is that the cell contains some resistance. The EMF can thus be defined as the driving potential within any electrical or electronic source, irrespective of internal resistance. When measured with very high resistance and no load, it is practically the voltage visible on the source’s output, such as a battery. It is the cell’s internal voltage.
Difference between electromotive force and potential difference
The potential difference and the electromotive force (EMF) are energy forms. One of the main differences between EMF and the potential difference is that the former is created by converting another form of energy into electrical energy, while the latter is caused by converting electrical energy into other kinds of energy. The comparison chart below explains some of the other distinctions between them.
Main differences between electromotive force and potential difference
1. Electromotive force is the amount of energy per unit charge obtained in a circuit from an electric or non-electric source while the potential difference is the computed difference in energy transmitted from one point to another in a circuit.
2. Michael Faraday discovered the electromotive force in 1830 after studying the chemical reaction between two electrodes and electrolytes, while the potential difference is determined by Alessandro Volta’s theory’s success rate.
3. Work/Charge (EMF = W/Q) is the electromotive force formula. The Voltage=Current x Resistance (V = IR) formula calculates the potential difference.
Conclusion
The EMF of a source is the amount of energy per unit charge produced in an electric or non-electric field. It is a cause determined by electrochemical cells and magnetic field variations. When there is no current flow in a circuit, electromotive force takes on a constant shape. Its SI unit is volts, and it is symbolised as V. The energy difference between two places in a circuit is the potential difference. The potential difference is written as PD and is measured in volts.
