1eV = ………………… Joule.

Hint: First of all we should know about Energy, as this is the unit of energy. In physics, the term energy is referred to as the quantitative property that must be transferred to the body in order to perform some work. It is a conserved quantity and from the law of conservation of energy we can say that the Energy can neither be created nor can it be destroyed, it can only transform from one body to the other.

Complete answer:
Electron volt, a unit of energy commonly used in atomic and nuclear physics, equal to the energy gained by an electron (a charged particle carrying unit electronic charge) when the electrical potential at the electron increases by one volt. The electron volt equals $1.6\,\, \times \,\,{10^{ - 19\,}}\,Joule$ or $1.6\,\, \times \,{10^{ - 12}}\,erg$. We can also say that 1 eV is defined as the energy gained by an electron when it has been accelerated by a potential difference of 1 volt.

Hence, the value of 1 eV =$1.6\,\, \times \,\,{10^{ - 19\,}}\,Joule$

Additional information:
Difference between Electric Potential and Electric Potential Energy: The major difference between the electric potential and electric potential energy is that the Electric potential at a point in an electric field is the total amount of work done in bringing a unit positive charge from infinity to that point, whereas the electric potential energy is the energy that is required in order to move a charge against the electric field.

Note: Electron volt in short eV is the unit of energy. The derived unit of Energy is Joule in the International System of units or SI units. Relation between eV And Joule is proportional. If we will make some changes in the value of eV then it will change the Joule equivalent value in the same proportion.