Question

Calculate the number of electrons constituting one coulomb of charge.

Answer 1

Hint: Every static charge has an electrostatic field around it. By nature, most bodies exist neutrally; this means they have equal numbers of positive and negative charges. When a body has more electrons then it is negatively charged but if it has less number of electrons, then it is negatively charged.
Formulas used:
$e=1.6\times {{10}^{-19}}C$
$n=\dfrac{1\,C}{1.6\times {{10}^{-19}}\,C}$

Complete answer:
When force acting between two charges is $\dfrac{1}{4\pi {{\varepsilon }_{0}}}N$(Here, ${{\varepsilon }_{0}}$ is the permittivity of free space) which are kept $1m$ away from each other, then the magnitude of charge on both the charges is said to be $1\,C$.
Charge is the property of a material by virtue of which it experiences force due to an electric field. Its SI unit is coulomb ($C$).
The magnitude of charge of one electron is-
$e=1.6\times {{10}^{-19}}C$
Therefore, the number of electrons in $1\,C$ charge will be-
$\begin{align}
  & n=\dfrac{1\,C}{1.6\times {{10}^{-19}}\,C} \\
 & \Rightarrow n=\dfrac{{{10}^{19}}}{1.6} \\
 & \Rightarrow n=0.625\times {{10}^{19}} \\
 & \therefore n=6.25\times {{10}^{19}} \\
\end{align}$
Therefore, the number of electrons in $1\,C$ charge is $6.25\times {{10}^{19}}$.

Additional information:
The force that exists between two charges is directly proportional to the magnitude of the charges and inversely proportional to the square of the distance between them, this is given by the coulomb’s law. Repulsive force exists between two like charges whereas attractive forces exist between two unlike charges. The work done to bring a unit charge from infinity to a point in the field of a charge is called the electric field of that charge.

Note:
Each electron has a negative charge therefore, by convention, the flow of current is taken opposite to the flow of electrons as current constitutes positive charge. A unit charge is taken as the standard charge when electric field or force due to electrostatics has to be calculated.