Question

A body has 80 micro-coulomb of negative charge. Number of additional electrons on it will be:
A. $8 \times {10^{ - 5}}$
B. $80 \times {10^{15}}$
C. $5 \times {10^{14}}$
D. $1.28 \times {10^{ - 17}}$

Answer 1

Hint: The smallest charge that can exist is the charge of an electron. Therefore, electric charge always exist as an integral multiple of electronic charge (e = $1.6 \times {10^{ - 19}}C$).
This is also known as the quantum nature of the charge.
→ q = ±ne
where n=0,1,2,3$ \ldots $

Complete step by step solution:
The charge on one electron is $1.6 \times {10^{ - 19}}C$
If n is the number of additional electrons. It can be calculated using quantization of charges as:
Thus the number of electrons is given as $ = \dfrac{{{\text{Total charge}}}}{{{\text{Charge on one electron}}}}$
Q = ne
One coulomb is equal to the amount of charge from a current of one ampere flowing for one second. One coulomb is equal to the charge on $6.241 \times {10^{18}}$ protons. The charge on 1 proton is $1.6 \times {10^{ - 19}}C$. Conversely, the charge of an electron is $ - 1.6 \times {10^{ - 19}}C$.
${\text{1Coulomb = 1}}{{\text{0}}^{{\text{ - 6}}}}{\text{micro - coulomb}}$
$\begin{gathered}
   = \dfrac{{80 \times {{10}^{ - 6}}}}{{1.6 \times {{10}^{ - 19}}}} \\
   = 5 \times {10^{14}} \\
\end{gathered} $

Therefore, number of additional electrons on the body will be $5 \times {10^{14}}$.

Note:According to the Law of conservation of charge, the charge is neither created nor destroyed. It can only be transferred from one system to another.

The basic cause of quantization is that only an integral number of electrons can be transferred from one body to another on rubbing.

When an object loses some electrons, the remaining object is now positively charged because it has an excess of photons. Atoms that have lost electrons and become positively charged are called positive ions, and atoms that have gained electrons and become negatively charged are called negative ions.

Atoms are electrically neutral because they have equal numbers of protons and electrons. If an atom gains or loses one or more electrons, it becomes an ion.