Question

Spot welding is used to fuse two sheets of metal together at one small spot. Two copper electrodes pinch the sheets together at a point and then run a huge electric current through that point. The two sheets melt and flow together to form a spot weld. Why does this technique work only with relatively poor conductors of electricity such as stainless steel and not with excellent conductors such as copper?

Answer 1

The power deposited in a metal is proportional to its electric resistance, so high-resistance metals heat more.