Question

From the following options, what is the value of ${\text{1eV = ?}}$
(a). ${\text{1}}{\text{.9}} \times {10^{ - 16}}J$
(b). ${\text{26}}{\text{.6}} \times {10^{ - 31}}J$
(c). ${\text{1}}{\text{.6}} \times {10^{ - 19}}J$
(d). $2.2J$

Answer 1

Hint: Electron volt basically is a unit of energy. This is related to the electron. It is the work done on the electron to move the electron through a potential difference of $1volt$. In other words electron volt is equal to the energy gained by an electron when the potential(electrical) at that electron raised by $1volt$.

Complete step-by-step solution -
Fundamentally, by theory we have,
${\text{1eV = 1}}{\text{.6}} \times {10^{ - 19}}J$
So, in the above question the option (C) is the correct answer.
Let us assume that there are two plates kept side by side in the same plane, one plate is negatively charged and another is positively charged, and they are differing by one volt. Let say one plate is 0volt and another volt is 1volt. Now if an electron moves from plate 1 to plate 2 then it will travel through a potential difference of 1volt. Then the energy acquired by this single electron to move through 1 volt of potential difference is the electron volt.
i.e.$U$=electric potential= charge× potential difference
so here it is ${\text{U = eV}}$
here in this example we have taken the potential difference=1volt=$\dfrac{{1{\text{J}}}}{{1C}}$
and the charge on the electron is ${\text{1}}{\text{.6}} \times {10^{ - 19}}C$.
So now , ${\text{U}}$=${\text{1}}{\text{.6}} \times {10^{ - 19}}C$×$\dfrac{{1{\text{J}}}}{{1C}}$
Coulombs will cancel each other and
Finally, ${\text{U = 1}}{\text{.6}} \times {10^{ - 19}}J$
This is known as ${\text{1eV}}$.

Note: Use of electron volt is done by the astronomers to measure the energy of the electromagnetic radiation or photons, in the calculation of the radiations x-rays and gamma rays of the electromagnetic spectrum, it is also used in measuring the difference in atomic and molecular energy states which give rise to ultraviolet. It is used by the particle physicist as a unit of energy.