91Ó°ÊÓ

Electric charge can exist only as an integral multiple of charge on an electron.The formula of the charge is given by,

$\mathit{Q}\mathbf{=}\mathbf{Â\pm }\mathit{N}\mathit{e}$

Here, Nis an integer, and eis the charge of the electron.

Given that the rate of flow of the charge in the lighting is$r=20,000\mathrm{C}/\mathrm{s}$ for time $t=100\mathrm{μ}s$. The charge flow is given by the formula $Q=rt$.

Substitute the rate of flow and the time in the above formula to get a charge flow.

$$\begin{gathered} Q=20,000\mathrm{C}/\mathrm{s}×100×{10}^{-6}\mathrm{s} \\ =2.0\mathrm{C} \end{gathered}$$

Hence, the charge flow between the ground and the cloud is 2.0 C.

The number of electrons,$n_e$ is given by the formula $n_e=\frac{Q}{e}$.

Substitute the charge flow$Q=2.0\mathrm{C}$ and the charge of electron$e=1.60×{10}^{-19} \mathrm{C}$ in the above formula to get the number of electrons.

$$\begin{gathered} n_e=\frac{2.0}{1.60×{10}^{-19}\mathrm{C}} \\ =1.25×{10}^{19}\mathrm{electron} \end{gathered}$$

Hence, the electron flows during this time is $1.25×{10}^{19}$electron .