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Difference Between Electromotive Force and Potential Difference

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Last updated date: 04th Mar 2024
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Unlocking the Potential of Physics of Electricity and Electric Potential

There are two major potential differences between the battery terminals that we experience when working with batteries and cells in the actual world. These potential differences are brought on by the battery's non-ideal properties, which raise the internal resistance. Such potential differences are measured using a potentiometer. E.M.F. and the potential difference of a cell are the names for these various values. We need to examine the resistance provided by the battery and the circuit in order to comprehend why this occurs. Let's take a closer look at these ideas.

What is Electromotive Force: An In-Depth Analysis

Electromotive force (emf) is the amount of energy per unit charge that an electrical source, like a battery or a generator, imparts. It is not a forced concept, but an electrical potential produced by an electrochemical cell or a shifting magnetic field. Furthermore, according to the Faraday law, the induced emf is what causes the electromagnetic field to expand. The value of emf, on the other hand, stays the same throughout.


Alternatively, electromotive force can also be described as a measure of how much energy is provided to each coulomb of charge. Electromotive force is the term used to describe emf. Electromotive force, often known as emf, is the force inside a voltage source that pushes current around a circuit. It is a property of all energy sources capable of pushing electric charge around a circuit. The amount of energy a cell supplies to the unit charge is known as the electromotive force, or emf. E stands for electromotive force.


Any of these devices can deliver current when resistance is connected to them and cause potential differences across their terminals regardless of the energy source. It is commonly known that an electric field created by a potential difference causes charges to move, which then results in current flow. As a result, emf refers to the potential difference created when no current is flowing.


Potential Difference: The Fundamental Cause of Electric Current

The potential difference between a battery's terminals is equal to the voltage difference between two points in a circuit. It is the transfer of electric energy along a path from one point to another. For instance, when a conductor is subjected to current, the free electrons roam about, creating an energy difference across the part and enabling the positive charge to flow in the external circuit. Electrical potential difference is the term used to describe this.


Characteristics of Electromotive Force and Potential Difference:

Following are some of the detailed characteristics about electromotive force. These are:


  • Formula for electromotive force is $\epsilon = V + Ir$ where V is the cell's voltage. I stands for current via the circuit, r for internal cell resistance, and $\epsilon$ for electromotive force.

  • Volt is used to measure electromotive force.

  • emf is calculated as the number of Joules of energy required by the source divided by each Coulomb to allow a unit electric charge to cross the circuit.

  • The ratio of work completed on a unit charge is known as emf. Hence, emf has the dimensions M1L2T-3I-1


Following are some of the detailed characteristics about potential difference. These are:


  • Potential difference is not constant throughout the circuit.

  • The resistance of the wire, the quantity of battery cells, and the separation between the points in a circuit all tend to affect the potential difference between the two points.

  • Formula for the potential difference is $V=IR$ where V= potential difference applied, I is the current and R is the resistance in the circuit.

  • The dimensional formula for potential difference is M1L2T-3I-1


Distinguish Between Potential Difference and EMF:

S.No

Category

Potential difference

Electromotive force


Definition

The potential difference between a battery's terminals is equal to the voltage difference between two points in a circuit.

Electromotive force (emf) is the amount of energy per unit charge that an electrical source, like a battery or a generator, imparts when no current is flowing


Formula

$V=IR$ where V is the potential difference


$\epsilon = V + Ir$ where $\epsilon$ is the electromotive force


Unit of measurement

Unit of measurement is Volt(V)

Unit of measurement is Volt(V)


Resistance

Resistance is one of the essential factors in determining potential difference across the ends in the circuit.

The resistance of the circuit has no bearing on electromotive force.


Magnitude

This is always less than the electromotive force owing to factors in the electrical circuit which affect potential difference.

Electromotive force is greater than potential difference because it occurs when no current is flowing.


Summary

It is crucial to distinguish between potential difference and emf. because these are two key ideas in the chapter on current electricity. The energy per unit charge generated in an electric or non-electric field is what is referred to as a source's emf. Electrochemical cells and changes in the magnetic field are the cause. Electromotive force assumes a consistent form in a circuit when there is no current flowing through it. Volts is its SI unit, and it is denoted by the letter V. The potential difference in a circuit is the energy difference between two points. The p.d. stands for potential difference and is expressed in volts.

FAQs on Difference Between Electromotive Force and Potential Difference

1. What is electromotive force and potential difference? Explain electromotive force and potential difference.

The work performed on a unit charge is referred to as emf. Whereas, The potential difference between a battery's terminals is equal to the voltage difference between two points in a circuit. To explain electromotive force and potential difference, formula of emf is $\epsilon = V + Ir$ where V is the cell's voltage. I stands for current via the circuit, r for internal cell resistance, and $\epsilon$ for electromotive force. Formula for the potential difference is $V=IR$ where V= potential difference applied, I is the current and R is the resistance in the circuit.

2. What are electromotive force and potential difference difference?

Some electromotive force and potential difference difference can be illustrated in the following way:


  • The potential difference is the calculated difference in energy  from one point to another in a circuit, whereas electromotive force is the amount of energy per unit charge acquired in a circuit from an electric or non-electric source.


  • While Alessandro Volta's theory predicts the potential difference, Michael Faraday discovered the electromotive force in 1830 after seeing the chemical reaction between two electrodes and electrolytes.

3. Is Electromotive Force being negative a possibility?

Certainly, a negative electromotive force is possible. As an illustration, imagine that an inductor is producing an electromotive force that is opposing the incoming power. Because the direction of flow is against the real power, the generated emf is then interpreted as negative. Consequently, the electromotive force is capable of being negative.