Chapter 20, Problem 1STP

To determine

To Choose: The correct option.

Answer to Problem 1STP

D. $4.7\times {10}^8\text{electrons}$

Explanation of Solution

Given:

The net charge, $Q=7.5\times {10}^{-11}\text{C}$

Formula used:

If the charge on an electron is $q_e$ and the number of electrons is $n$ , then the total charge of these electrons is,

  $Q_{tot}=q_{e}n$

Calculation:

Now, it is known that the charge on an electron is,

  $q_e=1.6\times {10}^{-19}\text{C}$

Then, the number of number of electrons removed to have a net charge of $7.5\times {10}^{-11}\text{C}$ will be,

  $\begin{array}{c}n=\frac{Q}{q_e}\\ =\frac{7.5\times {10}^{-11}}{1.6\times {10}^{-19}}\\ \approx 4.7\times {10}^8\end{array}$

Conclusion:

Thus, the number of number of electrons removed to have a net charge of $7.5\times {10}^{-11}\text{C}$ is $4.7\times {10}^8$ .