$(a)$ Explain the meaning of the statement 'electric charge of a body is quantised'.
$(b)$ Why can one ignore quantisation of electric charge when dealing with macroscopic, i.e., large-scale charges?

(N/A) The statement 'electric charge of a body is quantised' means that the electric charge of any body can only exist in integral multiples of the elementary charge $e$ (the charge of an electron). Mathematically, $q = ne$, where $n$ is an integer $(n = 0, \pm 1, \pm 2, \dots)$ and $e \approx 1.6 \times 10^{-19} \ C$. This implies that charge is not continuous but discrete.
$(b)$ On a macroscopic scale, the charges involved are extremely large compared to the elementary charge $e$. For example, a charge of $1 \ \mu C$ consists of approximately $6.25 \times 10^{12}$ electrons. Because the number of charges is so vast, the discrete nature of the charge becomes negligible, and the charge can be treated as a continuous quantity for all practical purposes.