Why Are Wires Made of Copper?

Step 1 of 5

A metal's outer electrons are not held tight.

In copper, each atom lets its outermost electron wander. The result is a fixed grid of atoms sitting in a sea of electrons that are free to move — and moving electrons are electricity.

Step 2 of 5

A current is a slow drift.

Switch a light on and it comes on immediately, but the electrons themselves crawl along slower than a snail. The push travels almost instantly; the electrons barely move at all.

Step 3 of 5

Silver is better, and nobody uses it.

Silver conducts slightly better than copper. It is also far too expensive to run through the walls of every house, so copper wins on price by an enormous margin.

Step 4 of 5

It bends without snapping.

A wire has to be pulled through walls, bent round corners and squashed into plugs. Copper can be drawn into thin wire and bent repeatedly without breaking, which most good conductors cannot.

Step 5 of 5

Resistance turns electricity into heat.

The drifting electrons keep bumping into the atoms, and every bump makes heat. In a wire that is waste; in a kettle element or a toaster it is precisely the point.

Overhead power lines are aluminium, not copper. Over hundreds of kilometres, being light matters more than conducting slightly better.