Mention the $SI$ unit and value of fundamental charge. Write its smaller units.

(N/A) The electric charge of an electron is called the fundamental charge. Its symbol is $e$ and its charge is negative.
In the International System $(SI)$ of units,the unit of charge is the coulomb,denoted by the symbol $C$.
One coulomb is defined as the charge flowing through a wire in $1 \ s$ when the current is $1 \ A$ (ampere).
The value of the fundamental charge is $e = 1.602192 \times 10^{-19} \ C$. In general,it is taken as $e = 1.6 \times 10^{-19} \ C$.
There are approximately $6.25 \times 10^{18}$ electrons in a charge of $-1 \ C$.
In electrostatics,smaller units of charge are:
$1 \ mC$ (milli coulomb) $= 10^{-3} \ C$
$1 \ \mu C$ (micro coulomb) $= 10^{-6} \ C$
$1 \ nC$ (nano coulomb) $= 10^{-9} \ C$