A conductor is a material that allows electric current to flow easily. Metals are the classic example, because they have free electrons that can move through the lattice. Copper, silver, gold, and aluminum are all good conductors. Silver is the best, but copper is cheaper and nearly as good, which is why most electrical wiring is copper. Conductors are essential to every electrical device, from a phone charger to a power grid.

Conductivity varies widely. Copper conducts about 100 million times better than glass. That difference is why wires are copper and insulators are glass or plastic. Conductors also conduct heat, for the same reason: free electrons carry both charge and energy. Superconductors are a special class of conductors with zero resistance below a critical temperature. They can carry current without losing energy, which makes them useful for MRI machines and particle accelerators. The search for room-temperature superconductors is one of the biggest challenges in condensed matter physics.

Conductor facts

• Free electrons. Carry charge through the material.
• Metals. Copper, silver, gold, aluminum.
• Superconductors. Zero resistance below a critical temperature.
• Heat. Conductors also conduct heat well.

A conductor is not the same as a wire. A wire is a conductor shaped into a useful form, often with insulation around it.