Electric Charges

Electric charges are either positive or negative. The like charges repel, the opposite attract. Charge is conserved in the sense that positive and negative charges are created or destroyed always in pairs. Inside a conductor the atoms are neutral at absolute zero temperature but at room temperature they shed one or sometimes more electrons and become positive. The released negative electrons are free to move but the total conductor is still neutral because there are exactly as many negative electrons in the interior as there are positive atoms. On the average, the spacing of electrons inside a neutral wire is exactly the same as that of singly ionized positive atoms.

Electric charges are surrounded by electric force fields in addition to their gravitational fields. While the gravitational interaction of charges inside the wire is present it is so minute in comparison with electric forces that we will consider only the latter.