What term describes a metal element that produces light when heated?

The term that describes a metal element that produces light when heated is filament. In the context of electrical engineering and lighting, a filament is typically made from a metal such as tungsten, which has high melting points and excellent conductivity.

When an electric current passes through the filament, it heats up to a temperature where it begins to emit visible light, a process known as incandescence. This principle is the basis for traditional incandescent light bulbs, where the filament is the primary source of light due to the intense heat generated by the electrical resistance.

The other terms are related to electricity and materials but do not correctly describe the phenomenon of light production through heating. A resistor is a component used to resist the flow of electric current, conductors are materials that allow electricity to flow with minimal resistance, and insulators are materials that prevent the flow of electricity. In this context, only the filament specifically relates to the generation of light when heated.