Dhristi JEE 2022-24

What is Electron-Volt?

The electron volt is not a frequently used unit, but it plays a vital role in electricity and magnetism, nuclear physics, etc. Now the question that arises is what is an electron volt? Basically, the electron volt is a unit of energy and is abbreviated as eV. 


In physics, an electronvolt is the amount of kinetic energy required by a single electron accelerating from rest through an electric potential difference of one volt. It is abbreviated as eV. 


An electron volt is a small unit of energy. When we want to move the charge having a value of 1 electron from lower potential to higher potential, then the charge will accelerate with some kinetic energy of 1eV. The electron volt (eV) is defined as: an electron volt is the amount of energy required to move a charge equal to 1e⁻ across a potential difference of 1eV.


Value of 1eV

  • We know that energy or the work done is also measured in terms of joules, abbreviated as J. 

  • The electron volt (eV) and Joules (J) both are units of energy. We use both units depending upon the need for calculations.

  • An electron volt is a unit of energy and the Joule is the SI unit of energy. Both Joules and eV can be interpreted in terms of one another.

  • Joule is most commonly used in the measurement of energy and eV is mostly used in calculating the energy of atomic energy levels.

  • Now, the value of 1eV is given by:


We know that in order to move an electron with a potential difference of 1V, then the amount of work done is,


\[\Rightarrow W = q\Delta V = 1e^{-} C (1V)\frac{J}{C}\]


\[\Rightarrow W 1eV = 1.6 * 10^{-19} J \]


  • Therefore, 1 electron volt is equal to\[1.6 * 10^{-19} Joules \].


Relation Between 1eV and Joules

Both electron volt and the joules can be related by unit conversions. One should always keep in mind that unit conversion can be done if and only if both measuring units are of the same scale. Here, both electron volt and joules are the units of energy and hence they are interchangeable.


So, the electron volt and joules have a relation given by:


\[\Rightarrow 1eV = 1.6 * 10^{-19} J \]


Therefore the value of one electron volt is equal to \[1.6 * 10^{-19} J \].



Definition

Formula

Symbol

Electron volt

1 electron volt is the energy change that takes place when a unit charge ( 1 electron) is moved through a potential difference of 1 volt.

1eV = 1.602 * 10-19

eV

Joule

1 Joule is the work done by a force of 1 newton in the direction of its motion covering a distance of 1 meter.

\[ 1J = 6.2415 * 10^{-18} eV\]

J


The eV-Joule Conversion is very helpful in solving physics problems. The eV to Joule conversion table is given below:


eV to Joule Conversion

Energy in eV

Energy in joules

1 eV

\[1.60218 * 10^{-19} J\]

2 eV

\[3.2044 * 10^{-19} J\]

3 eV

\[4.8065 * 10^{-19} J\]

4 eV

\[6.4087 * 10^{-19} J\]

5 eV

\[8.0109 * 10^{-19} J\]

6 eV

\[9.6131 * 10^{-19} J\]

7 eV

\[1.1215 * 10^{-19} J\]

8 eV

\[1.2817 * 10^{-17} J\]

9 eV

\[1.442 * 10^{-18} J\]

10 eV

\[1.6022 * 10^{-18} J\]

50 eV

\[8.0109 * 10^{-18} J\]

100 eV

\[1.6022 * 10^{-17} J\]

500 eV

\[8.0109 * 10^{-17} J\]

1000 eV

\[1.6022 * 10^{-16} J\]


The Joule-eV Conversion is very helpful in solving problems related to electric charge in physics. The table for Joule to eV conversion is given below:


Joule to eV Conversion

Energy in Joules

Energy in eV

1 J

\[6.242 * 10^{18} eV\]

2 J

\[1.248 * 10^{19} eV\]

3 J

\[1.872 * 10^{19} eV00\]

4 J

\[2.497 * 10^{19} eV\]

5 J

\[3.121e * 10^{19} eV\]

6 J

\[3.745 * 10^{19} eV\]

7 J

\[4.369 * 10^{19} eV\]

8 J

\[4.993 * 10^{19} eV\]

9 J

\[5.617 * 10^{19} eV\]

10 J

\[6.242 * 10^{19} eV\]

50 J

\[3.121 * 10^{20} eV\]

100 J

\[6.242 * 10^{20} eV\]

500 J

\[3.121 * 10^{21} eV\]

1000 J

\[6.242 * 10^{21} eV\]


Solved Examples:

1: A Particle Carrying Charge of 4e Falls through a Potential Difference of 4V. Calculate the Energy Acquired by the Particle.

Sol: We know that whenever an object falls from a higher level to a lower level the potential energy stored will release in the form of kinetic energy. Thus the energy acquired by the particle will be kinetic energy.

Given,

Charge of the particle = q = 4e 


The potential difference between two levels = ΔV = 4V 


We need to calculate the kinetic energy, then:


\[\Rightarrow K.E = q\Delta V\]


\[\Rightarrow  K.E = (4e)(4)\]


\[\Rightarrow  K.E = 16 e\]


\[\Rightarrow  K.E = 16 * 1.6  * 10^{-13} eV\]


\[\Rightarrow  K.E = 25.6 eV\]



Therefore, the energy acquired by a charge of 4e when it falls through a potential difference of 4V is 25.6eV.


2: Define Electron Volt and Prove that 1eV = \[10^{-19} J\].

Sol:  Electron Volt definition: An electron volt is the amount of energy required to move a charge equal to 1e⁻ across a potential difference of 1eV. This is how we define one electron volt.


Now, to prove that the value of 1eV is \[10^{-19} J\] we will use the unit conversions for a better understanding.


Now, we know that in order to move an electron with a potential difference of 1V, then the amount of work done is,


\[\Rightarrow W = q\Delta V = 1e^{-} C(1V) \frac{J}{C}\]


\[\Rightarrow W = 1eV = 1.6 * 10^{-19} Joules \]


Therefore, 1 electron volt is equal to 1.6 x 10⁻¹⁹ Joules.


3: What is the Value of One Mega Electron Volt?

Sol: 1 mega unit = \[10^{6} eV\]

Then, 1 mega electron volt is given by,


\[\Rightarrow 1MeV = 10^{6} * 1.6 * 10^{-19}\]


\[\Rightarrow 1MeV = 1.6 * 10^{-13} eV\]


Therefore, the value of one mega electron volt is  \[10^{-13} eV\].


The article covers all the important concepts of electron volt such as its conversion from one unit to another. Solved examples are also given in the above article that will help students to understand the unit of electron-volt.

FAQs on Electron Volt

1. Where can students find useful information regarding electron volt and its conversion?

Students can find everything they need on the Vedantu app or website. These study materials are created by professionals and the content is accurate and reliable. These study materials are completely free and there is no cost at all. All students just have to sign in and then they will be able to download what you want in pdf format. Students can find information regarding the electron volt, its conversion, and a whole lot more!

2. What is an electron volt?

In physics, an electronvolt is the amount of kinetic energy required by a single electron accelerating from rest through an electric potential difference of one volt. It is abbreviated as eV. In simple words, 1 electron volt is the energy change that takes place when a unit charge (1 electron) is moved through a potential difference of 1 volt.

3. What is the relation between electron volt and Joule?

Both electron volt (eV) and the joules (J) are units of energy in two different systems. Students must keep in mind that the conversion between different units can only be done if both measuring units are of the same scale. In this case, both electron volts and joules are the units of energy and hence they are interchangeable. The electron volt and joules have the following relation: \[1eV =  10^{-19} J\]  Therefore the value of 1 electron volt is equal to \[10^{-19} J\].

4. What is the difference between electron volt and joule?

Electron volt and joule, both are units of energy in different systems. The difference between electron volts is given below:


Electron volt- 1 electron volt is the energy change that takes place when a unit charge ( 1 electron) is moved through a potential difference of 1 volt. It is represented by the symbol is eV


Joule- 1 Joule is the work done by a force of 1 newton in the direction of its motion covering a distance of 1 meter. It is represented by the symbol J.

5. How can you define 1 Joule?

1 Joule is the amount of work done when a force of 1 Newton is applied on a body and it covers a distance of 1m in the direction of the applied force. In simple words, 1 Joule is the work done by a force of 1 newton in the direction of its motion covering a distance of 1 meter. Joule is the SI unit of work. It is represented by the symbol J.

6. Is Electron Volt and Volt the Same?

No, An electron volt is the unit of energy, but a volt is the derived unit of potential difference. Therefore, they are not the same.

7. How Do We Convert Electron Volt (eV) to Volts?

\[1eV = 1.6 * 10^{-19} V \]

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