Question

$\frac{4}{25}$ coulomb of charge contains ________ electrons.

• A. ${10}^{15}$
• B. ${10}^{18}$
• C. ${10}^{20}$
• D. none of these

Answer 1

The correct option is B

${10}^{18}$

Step 1: Given data:

Charge given $q=4/25\mathrm{C}$
Charge on electron $\mathrm{e}=1.6\times {10}^{-19}\mathrm{C}$.

Step 2: Calculating the number of electrons,

The formula for quantization of charge is given as $q=ne$.

Where,

$q$ is the amount of charge in Columbus's

$n$ is the number of charges

$e$ is the charge on the electron.
$n$ can be calculated as,

$n\mathit{=}q\mathit{/}e\mathit{=}\frac{\mathit{4}}{\mathit{25}}\mathit{\times }\left[\frac{1}{1.6\times {10}^{-19}C}\right]\mathit{=}{\mathit{10}}^{\mathit{18}}$ which is the number of electrons.

Therefore, $\frac{4}{25}$ coulomb of charge contains ${10}^{18}$ electrons.

Hence, option $B$ is correct.