Incandescent bulbs have become-literally-a fixture of modern life. We’re used to them, but they’re a long way from an ideal light source.
A lit incandescent bulb has one predominant feature. Sure, it’s light in terms of its weight. And it’s fragile. It’s even bright. But, more than anything else, it’s hot.

Heat is a measure of how energetically atoms are moving within an object. Even in solids, atoms move around, bumping against each other. If the atoms within an object are relatively stationary, the object is cool, while a hot object is full of atoms sliding back and forth. In a burner on an electric range, for example, electrons push through the coil, crashing into other atoms along the way. These collisions put the electrons in excited states, and they release that energy as they transition back to a lower energy state.

A River of Electrons
The electrical current is kind of like a river, with some electrons flowing quickly and smoothly, while others bump and crash their way along. Then electrons that have been crashing along find some open space and rush by, while some of the quickly flowing electrons crash and slow down. So at any instant some electrons are moving very quickly, while others are moving slowly—but most are toodling along somewhere in between.

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Originally published at Suite 101, 29 MAR 2011