. Define electron volt (eV). Derive its relation with SI unit of energy?

1. Definition of Electron Volt (eV):

An electron volt (eV) is a unit of energy that is particularly convenient in atomic and nuclear physics, as well as in particle physics. It is defined as the amount of kinetic energy gained by a single electron when it is accelerated from rest through an electric potential difference of one volt.

2. Derivation of its relation with SI unit of energy (Joule):

The energy E gained by an electron in moving through a potential difference V is given by the equation:

E = qV

where q is the charge of the electron.

The charge of an electron is approximately 1.602 x 10^-19 coulombs.

Therefore, if we substitute this value into the equation and consider a potential difference of 1 volt, we get:

E = (1.602 x 10^-19 C) x (1 V) = 1.602 x 10^-19 joules

So, 1 electron volt (eV) is equivalent to 1.602 x 10^-19 joules (J). This is the relation of eV with the SI unit of energy.