Question

A strong lightning bolt transfers $30C$ to Earth. How many electrons are transferred?

Answer 1

Hint: Charge is a property of matter, current also constitutes charge. Lightning consists of current. As current flows, so does lightning and charge is transferred to the ground. The charge constitutes electrons. Using unitary method and dividing the total charge by the charge of electrons, we can calculate the number of electrons.
Formulas used:
$1e=1.6\times {{10}^{-19}}C$

Complete answer:
Charge is the property of a material by virtue of which it experiences a force in an external electric field. Coulomb (C) is the SI unit of charge. Also, current constitutes charge. Charges have two types; negative charge and positive charge. Charge is mostly the flow of electrons which are negatively charged. The electron has a charge of-
$1e=1.6\times {{10}^{-19}}C$
Lightning is developed when the static electricity between the clouds makes one cloud to be positively charged and the other cloud to be negatively charged, hence current flows between them.
Given, a lightning bolt strikes the ground, it consists of $30C$. The number of electrons transferred to the ground from the lightning is the number of electrons that are present in $30C$ charge.
Using the unitary method, the number of electrons can be calculated as-
$\begin{align}
  & 1e=1.6\times {{10}^{-19}}C \\
 & \Rightarrow x\,e=\dfrac{30C}{1.6\times {{10}^{-19}}C} \\
 & \Rightarrow x=18.75\times {{10}^{19}} \\
\end{align}$
The number of electrons are $18.75\times {{10}^{19}}$.
Therefore, the number of electrons transferred from $30C$ to the ground is $18.75\times {{10}^{19}}$.

Note:
Current is the flow of positive charge and hence it is taken opposite to the flow of negative charge, by convention. Ground is the conductor of electricity that is why it attracts lightning. Lightning occurs when clouds rub against each other due to friction and a large static energy is developed between them which is then attracted by the Earth.