Question

A current of $1A$ is drawn by a filament of an electric bulb. What will be the approximate number of electrons passing through a cross section of its filament in 16 seconds?

• A. ${10}^{20}$
• B. ${10}^{19}$
• C. ${10}^{22}$
• D. ${10}^{23}$

Answer 1

The correct option is A ${10}^{20}$

Given:
Current, $I=1A$
$t=16s$
Since, $I=\frac{Q}{t}$
Where $Q$ is the total charge passing through a cross-sectional area.
Hence,
$1A=\frac{Q}{\left(16s\right)}$
$Q=16C$
Also, charge of an electron,
$e=1.6\times {10}^{-19}C$
Let the no. of electrons be $n$. Then, $I\times t=Q=n\times e$
$n=\frac{1\times 16}{1.6\times {10}^{-19}}$
$n={10}^{20}$electrons.