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Electric Potential Define I Formula I Electric Potential Difference

We cannot imagine our life without electricity. A day in the hot summer without a fan, a day in the kitchen without an oven or a mixer grinder, a day in the office without electricity. Imagine a day without electricity – How do we spend such a day? Electricity is an important part of human life and it is driven by Electric Potential. This post will discuss about What is Electric Potential, Electric Potential Difference, Formula, SI Unit and the difference between both.

What is Electric Potential?

Before understanding the word Electric Potential, let us know what electricity is. Electricity is the flow of electric charges which is responsible for producing electric current. An electric field is created wherever there is electric current.

What is Electric Potential

Electric Potential is a point in this electric field which is the work done in order to drive a unit positive charge from infinity to that particular point against the electric forces. It is also called Voltage. It is a scalar quantity and its SI unit is volts.

Therefore Electric Potential can be referred to as work done per unit of charge. This work is performed for bringing charge from the infinity point to a point placed in the electrostatic field but against the force of the field.


Fig. 1 – Introduction to Electric Potential and Charge 

To understand Electric Potential let us look into the above figure. ‘+q‘ is the charge in the above figure that has created an electric field. Electric Potential brings in the unit charge +q from the infinity area that is situated outside the electric field to any point within the electric field. It is to be noted here that the electrostatic force produced in the electric field will always be against the unit charge. Therefore to move from infinity to a place in the field or from one field to another some task is performed by the unit charge.

The conclusions that can be drawn in such case are as mentioned below:

  1. The work done is called Electric Potential at X (Vx) when the charge moves from infinity to point X
  2. The work done is called Electric Potential at Y (Vy) when the charge moves from infinity to point Y
  3. However when the work is performed to move the charge between point X and Point Y, then that is called the Potential Difference between x and y ( Vxy)

Formula to Calculate Electric Potential

Voltage or Electric Potential is calculated with the formula mentioned below:

Electric Potential or Voltage = Work Done / Unit Charge

The SI unit for Electric Potential is voltage or volts as

Volts = Joules / Coulomb = W / q = V

Therefore one can say that

1 Volt = 1 Joule / 1 Coulomb

And can be defined as 1 Joule of task performed to move 1 Coulomb of charge

Electric Potential Difference

Every electric charge possesses energy and it is known as Electrical Energy. The quantum of Potential Energy in the specific charge depends upon its potential. Charge with higher potential will have higher energy while one with lesser potential has lesser energy. Typically the current always moves downward namely from the higher potential to the lower potential. This difference between the two potential energy per unit of the charge is termed as Electric Potential Difference.

A potential difference is mandatory for the flow of the current and for creating electricity. This is normally maintained by a cell or a battery.


Fig. 2 – Symbol of Electric Cell

The higher potential in a cell is represented by the longer side and is also called a Positive Terminal. The shorter side is representative of lower potential and is also called as the Negative Terminal.

A voltmeter is used to measure the Electric Potential Difference. The voltmeter can be applied parallelly for measuring the voltage of the instrument.

A normal and common type of voltmeter looks as under:


Fig. 3 – Voltmeter Symbol


Electric Potential Difference can be defined as the work required for moving one unit charge from one point to another point in an electric field is called the Electric Potential Difference. A voltage difference is another name for an Electric Potential Difference.

In simple words, the Electric Potential Difference can be said to be a measure of electron pressure. The basis for the measure of electrons is formed on two parameters namely the way tightly the electrons are packed with each other and due to the mutual repulsion the intensity with which the electrons wish to move.


The formula to calculate Electric Potential Difference is as follows:

Vxy = Vx – Vy = (Wx – Wy) / q

However, it is not as simple as it appears to be to a layman person. To calculate the potential difference, first, it becomes essential to find out the number of electrons that have moved or charged and also the change in potential energy or the energy that is released. The charge or the movement is measured in Coulombs while the potential energy released or the change in energy is calculated through Joules.

Therefore the formula to calculate the Electric Potential Difference is

dV = dPE / q


dV = change in voltage. It is measured in voltage.

dPE = change in potential energy. It is measured in Joules

q = charge. It is measured in Coulombs

SI Unit of Electrical Potential

Alessandro Volta, an Italian physicist invented the first electric battery along with many other discoveries. The standard unit of Electric Potential and the Electric Potential Difference is named after this physicist. As discussed above one joule per coulomb is equal to one volt or voltage. The unit of energy is Joules while a standard unit of electric charge is Coulomb.

Joule can be defined as the quantity of energy required to accelerate or move a kilogram of mass across one meter of distance at a speed of 1 m/s per second. Coulomb can be referred to as a group of electrons. To give an example one can say that a smartphone battery when fully charged contains approximately 10000 Coulombs.

Ohm’s Law

Ohm’s Law is used to explain resistance. As per this law, the current that flows through the conductor is directly proportional to the voltage. However, the temperature and the conductivity should remain the same while the process is going on.

A new constant called Resistance is introduced when proportionality is removed.

Electric Potential Differential Formula

Fig. 4  – Ohm’s Law Representation

From the above figure, it can be concluded as

V = IR


V = Voltage through the conductor

I = Current that is flowing in the wire

R = Resistance by the conductor specified in ohms

Read about OHMs Law in detail

Difference Between Electric Potential and Electric Potential Difference

There is a thin line difference between Electric potential and the Electric Potential Difference. In fact, Electric Potential forms the basis for Electric Potential Difference.

The work done to move a unit charge from a point in infinity to a point placed in an electric field is called Electric Potential. However, while the unit charge moves in between the points in the electric field a potential is developed. This is called the Electric Potential difference. The SI unit for Electric Potential and an Electric Potential Difference is Voltage or Volts.

Electric Potential Difference Example

The simple and most used example of Electric Potential Difference in our daily lives is a 9 Volt battery. Millions and millions of electrons packed tightly with each other are stored on one side of the battery. However, the other side is kept empty for the electrons to move freely toward that side. Therefore when the two sides of the wire are attached from terminal to terminal, the electrons start moving from the high concentration or the packed area to the low concentration or the empty area. When the two sides get an equal number of electrons, their Electric Potential Difference becomes zero. Thus the battery goes off or becomes dead.

This is the simplest example to understand the Electric Potential Difference in a very easy manner.

Final Words

Therefore one can say that the potential difference in two points that refer to work done or involved and specific energy released for transferring a unit charge of electricity between two points can be referred to as Electric Potential Difference. Lightning in the sky is a huge example of the potential difference of electrons and has millions of voltage involved in it.

You May Also Like to Read:
How Electricity Reaches Our Homes – Various Paths in Distribution
Why High Voltage Transmission is Required Between Substations
Voltaic Cell – Construction, Types, How it Works, Applications, Advantages
Chakrasthitha is a B.E (Medical Electronics) and has work experience in MatLab and Lab View Software as Design Engineer at BCS innovations and Manipal hospital as Biomedical Engineer. She is an author, editor and partner at Electricalfundablog.


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