In
electrostatics, charges of this large magnitude are seldom encountered
and hence we use smaller units 1 mC (micro coulomb) = 10–6 C or 1 mC
(milli coulomb) = 10–3 C If the protons and electrons are the only basic charges in the
universe, all the observable charges have to be integral multiples of e Thus, if a body contains n1 electrons and n2 protons, the total amount
of charge on the body is n2 × e + n1 × (–e) = (n2 – n1) e Since n1 and n2
are integers, their difference is also an integer