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WHO TURNED
ON THE LIGHTS?

     What do most people think of when they hear the name Thomas Edison? The light bulb, of course. Invented by Edison in 1879, it was the most practical source of artificial light produced by man since the beginning of time. In the early 1800s, scientists in both the United States and Europe had experimented with hundreds of incan- descent electric lights. But they couldn’t get any of them to work, except perhaps for brief periods, until Edison succeeded.

     As hard as it was to develop, the incandescent electric light is basically a simple device. It con- sists of a coiled filament within a glass enclosure from which the air has been removed.

     The principle on which it is based is that a glowing filament gives off both heat and light. The hotter the filament, the brighter the light. Edison’s main problem was to find the right mate- rial to use for the filament. But he also had to create a good vacuum to prevent the filament from burning up.

     After finding that carbon filaments worked best, he managed to make the filament last longer and longer by removing more and more air from the bulb. We’re going to try something similar in this experiment on the light bulb.