Q : Why one can ignore quantisation of electric charge when dealing with macroscopic i.e. large scale charge ?
Sol : At the macroscopic level one deals with charges that are enormous compared to the magnitude of charge e . Since e = 1.6 × 10-19 C , a charge of magnitude , say 1μC contains something like 1013 times the electronic charge .
At this scale , the fact that the charge can increase or decrease only in units of e is not very different from saying that charge can take continuous value . Thus at the macroscopic level , the quantisation has no practical consequence and can be ignored .