Question

The number of electrons present in -1C of charge is:
$\begin{align}
  & \text{A}\text{. 6}\times \text{1}{{\text{0}}^{18}} \\
 & \text{B}\text{. 1}\text{.6}\times \text{1}{{\text{0}}^{19}} \\
 & \text{C}\text{. 6}\times \text{1}{{\text{0}}^{19}} \\
 & \text{D}\text{. 1}\text{.6}\times \text{1}{{\text{0}}^{18}} \\
\end{align}$

Answer 1

Hint: We have been provided with a charge which is -1C. To calculate the number of electrons use the expression of quantization of charge which will give a relation between number of charge, charge on electron. Put the values in the expression and get the answer.
Formula used:
Expression of quantization of charge is given by,
\[Q=ne\]
Where, Q is the charge on any body
n is an integer
e is the charge on an electron(fundamental charge)

Complete answer:
The question asked to find the number of electrons present in -1C of charge.
We know that charge on a body always exists as an integral multiple of the fundamental charge.
So, by quantisation of charge,
$q=ne\text{ or }n=\dfrac{q}{e}$
We have been provided with value of charge which is -1C and we know that charge on electrons, which is $1.6\times {{10}^{-19}}C$
Put values in above equation, we get
$n=\dfrac{q}{e}=\dfrac{-1C}{1.6\times {{10}^{-19}}C}=6\times {{10}^{18}}$electrons

So, the correct answer is “Option A”.

Additional Information:
The simplest way of understanding the quantisation of charge is firstly we have to understand what does quantized word mean?
Quantized means anything which is available or present in a fixed amount.
After the efforts of physicians we have to come to know that ‘the charge is quantized’, means charge is always available in fixed amounts and it does not vary.
The smallest charge that can exist independently is the charge on one electron which is $1.6\times {{10}^{-19}}C$ .

Note:
Quantization of charge is the principle that the charge of any object is the integral multiple of the elementary charge. Thus an object’s charge can be exactly 0e or 1e or -1e or 2e but not like 12e or -3.8e, etc. quantization term is usually ignored at macroscopic level, the reason is at that point, charges are taken to be continuous.