Question

When ${10}^{19}$ electrons are removed from a neutral metal plate, the electric charge on it becomes

• A. $-1.6\text{C}$
• B. $+1.6\text{C}$
• C. ${10}^{+19}\text{C}$
• D. ${10}^{-19}\text{C}$

Answer 1

The correct option is B $+1.6\text{C}$

Charge on an electron, $-1.6\times {10}^{-19}\text{C}$.
So if we remove an electron from a neutral plate, we remove a charge of $-1.6\times {10}^{-19}\text{C}$
The charge gained by the plate is equal to $+1.6\times {10}^{-19}\text{C}$.
So if we remove $n={10}^{19}$ electrons, the net charge $\left(q\right)$ on the metal is
$q=ne$
$\Rightarrow q={10}^{19}\times 1.6\times {10}^{-19}\text{C}$
$\Rightarrow q=1.6\text{C}$

$\begin{array}{c}\text{Why this question ?}\\ \text{Tip: The electric charge appearing on plate will follow}\\ \text{principle of quantization i.e.}q=ne\end{array}$