Question

what heats up and begins to glow?​

Answer 1

Answer:

The most famous example is an incandescent light bulb. Inside the glass bulb is small piece of metal (filament) made of tungsten. ... So hot, in fact, that it gives off enough energy to cause the filament to glow. This is the same reason that the cooking elements on an electric stove glow red when they heat up.

Answer 2

Answer:

When an iron bar is heated to a very high temperature, it initially glows red, and then as its temperature rises it glows white. ... At medium temperatures, say 1073 K (800 °C), the energy radiated by an object reaches a peak in the infrared, with a low intensity at the red end of the visible spectrum.