Positive and Negative Charge

(Section 5.1)

Electric charge is a fundamental property of certain of the elementary particles of which all matter is composed. All electric charges are either positive or negative. Like charges repel each other, unlike charges attract each other. Matter that has no overall charge is called neutral. In anything larger than an atom, this means that the number of protons and equals the number of electrons.

The unit of charge is the coulomb (C) and the charge on the electron is -1.6 x 10^-19 C. Since the smallest charges possible are that of the proton and the electron, all charges, of either sign, occur in multiples of e = 1.6 x 10^-19 C.