CHARGE

"Charge" is the stuff inside wires, but usually nobody tells us that all metals are always full of movable charge. Always. A hunk of metal is like a tank full of water. Shake a metal block, and the "water" swirls around inside. This "water" is the movable electric charge found inside the metal. In our science classrooms we call this by the name "electron sea," or even "electric fluid." This movable charge is part of all metals. In copper, the electric fluid is actually the outer electrons of all the copper atoms. In any metal, the outer electrons do not orbit the individual atoms. The electrons do not behave as textbook diagrams usually show. Instead, the atoms' outer electrons drift around inside the metal as a whole.

The movable charge-stuff within a metal gives the metal its silvery metallic color. We could even say that charge-stuff is like a silver liquid (at least it appears silver-colored when it's in metals. When it's within some other materials, the movable charges don't look silvery. "Silvery-looking charges" is not a hard and fast rule.)

Note that this charge-stuff is "uncharged", it is neutral. It's uncharged charge! Is this even possible? Yes. On average, the charge inside a metal is neutralized because each movable electron has a corresponding proton within a nearby atom. Each electron is very close to a proton. The electric force-fields from the two opposite charges cancel each other out. The overall charge is zero because equal quantities of opposite polarity are both present. For every positive there is a negative. But this doesn't mean that the charge-stuff is gone. Even though the average amount of charge inside a metal is cancelled out, we can still cause one polarity of charge to move along while the other polarity remains still. An electrical current is a flow of "uncharged" charges. Metal is made of negative electrons and positive protons; it's like a positive sponge soaked with negative liquid. We can make this "negative liquid" flow along.