The longest experiment Edison ever conducted was to research and invent the electric light. Edison tested nearly 1,600 materials, and finally successfully developed the electric light on October 21, 1879.
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The twists and turns of Edison’s invention of the electric light:
In 1874, two Canadian electrical technicians applied for a patent for an electric light: in a glass bulb The bottom was filled with nitrogen gas to emit light on the charged carbon electrode, but the electrical technicians did not have enough money to continue to perfect the invention, so the patent was sold to Edison in 1875. Edison purchased a patent and attempted to improve the filament.
Finally, in 1880, Edison produced a carbonized bamboo filament lamp that lasted 1,200 hours. However, the U.S. Patent Office ruled that Edison's invention of the carbon fiber incandescent lamp was invalid. After years of legal battles, Henry Goebbels won the patent, which Edison eventually purchased from Goebbels' impoverished widow.
In England, Swann sued Edison for patent infringement. It was later settled out of court and a joint venture was formed in 1883. Swann later sold his shares and patents to Edison.