Copper wire

Copper wire is copper pulled into a long, thin strand of exact thickness. Copper is used because it conducts electricity better than any metal except silver, and it is affordable, soft and easy to shape.

It starts as a thick rod of pure copper, about 8 mm across, cast and rolled in one continuous line. The rod is then drawn: pulled through a die, a hard block with a slightly smaller hole, then through the next die, and the next, each one thinning and lengthening the wire. The dies are made of tungsten carbide, or diamond for the finest sizes. Drawing makes the copper hard and springy, so it is usually annealed (heated and cooled) to soften it again.

In a TV, copper wire turns up wherever a coil or a thin link is needed. It is wound into inductors, the windings of a transformer and the voice coil of a speaker, usually as magnet wire with a thin coat of enamel so the turns don't short together. A precise, thin piece becomes the melting link in a fuse, and strands of it carry the current inside insulated wire.