Yes, Thomas Alva Edison did invent "a" light bulb, just that he was
not the first. It was Sir Joseph Wilson Swan who succeeded partly in his
first light bulb experiment using "carbonized paper as filament" in
1860.
So what prevented him from carrying on?
Due to the inadequacy of a strong vacuum and powerful batteries, he stopped his experiment and went on to another investigation, leaving his experiment undone. 15 year later, Swan went back to his earlier thought of the light bulb, with better vacuum and a replaced carbonized thread as the filament for carbonized paper, a real, working light bulb was out in 1878. However, the carbonized thread was affirmed and invented by Edison, and thus was credited most for the invention while Swan went on pursuing on other things after this "partly success" of the light bulb. Edison's effort, however, should never be underestimated. The last step to the discovery of the carbonized threat wasn't made overnight. how many nights, materials, ideas and time had he spent on one single key turning point.
So how does it really work?
In a common incandescent light bulb, an electric current flows through a double-spiral coil of very thin tungsten wire. As the electric charges in the current flow through this tungsten filament, they collide periodically with the tungsten atoms and transfer energy to those tungsten atoms. The current gives up its energy to the tungsten filament and the filament's temperature rises to about 2500° C. While all objects emit thermal radiation, very hot objects emit some of the thermal radiation as visible light. A 2500° C object emits about 12% of its heat as visible light and this is the light that you see coming from the bulb. Most of the remaining heat emerges from the bulb as invisible infrared light or "heat" light. The glass enclosure shields the filament from oxygen because tungsten burns in air.
--rabi.phys.virginia.edu/HTW/incandescent_light_bulbs.html
--DH., Casselberry, FL (and also KH)
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