Conductors and insulators

Beginner

Charges move freely in conductors but not in insulators.

In conductors (metals) outer electrons move freely; insulators (glass, plastic) hold them tightly. Semiconductors lie between.

Worked example

Copper wire conducts, rubber coating insulates.

Common mistake

Even insulators can be charged but charges stay in place.

In more detail

Conductors allow charge to move freely through them, as metals do, while insulators hold charge in place. Semiconductors fall between the two.

Copper wires conduct current, while plastic coatings insulate them.
Electronic devices use semiconductors to control current flow.
Power cables use copper, a conductor, while their plastic coating is an insulator that keeps the current inside.

Why are metals good conductors?

They have free electrons that can move through the lattice.

Are insulators perfect?

No, they conduct a tiny amount, and at high voltages they can break down.

Why is rubber used as an insulator?

Its electrons are tightly bound to atoms, so charge cannot move through it easily.