9.1.2—The charge on charge carriers is quantised

Electric charge occurs in discrete amounts q=ne, where n is an integer and e≈1.60×10⁻¹⁹ C.

Use the sign to identify positive or negative carriers and interpret n as a count, not a continuously adjustable fraction.

A charge of −3.2×10⁻¹⁹ C corresponds to two excess electrons.

The quantisation statement does not mean every macroscopic measurement visibly jumps by e; huge carrier counts make charge appear continuous.