Electric light bulb (or electric ball, tungsten lamp), its exact scientific name is incandescent lamp. The periphery of the bulb is made of glass, which keeps the filament in vacuum or low-pressure inert gas to prevent the filament from oxidation at high temperature. See incandescent lamp. It is generally believed that the electric light is American Thomas? Edison invented it. But if you examine the evidence carefully, another American, Henry? Goebbels (Heinrich? Bel) A reliable electric light bulb was invented with the same principles and materials decades before Edison, and many people made many contributions to the invention of electric light before Edison. 180 1 year, the British chemist David electrified the platinum wire to glow. He also invented the electric candle in 18 10, which was illuminated by an arc between two carbon rods. 1854 Henry? Goebbels used a carbonized bamboo filament and put it under a vacuum glass bottle to make it glow. Today, his invention seems to be the first incandescent lamp with practical value. The light bulb he tested at that time could last for 400 hours, but he didn't apply for the design patent in time.
1850, English Joseph? Wilson? Joseph Wilson Swan began to study electric lights. 1878, he obtained a British patent for a light bulb powered by carbon wire under vacuum, and started to set up a company in Britain to install electric lights in every household.
1874, two Canadian electrical technicians applied for a patent for electric lamps. They filled the glass bulb with nitrogen, and the electrified carbon rod made it glow. But they didn't have enough money to continue developing this invention, so they sold the patent to Edison on 1875.
Edison tried to improve the filament after buying the patent. 1879, he changed to carbon filament to make a light bulb, which successfully lasted 13 hours. By 1880, his carbonized bamboo filament bulb had been successfully maintained in the laboratory for 1200 hours. But in Britain, Swan sued Edison for patent infringement and won. Edison's electric light company in England was forced to make Swan a partner. But later Swan sold his rights and patents to Edison. In America, Edison's patent has also been challenged. The United States Patent Office once ruled that his invention had a criminal record and was invalid. Finally, after years of litigation, Edison obtained the patent right of carbon filament incandescent lamp.
Edison's greatest discovery was that tungsten was used as the filament instead of carbon. Later, in 1906, General Electric invented the manufacturing method of tungsten wire for electric lamps. Finally, the method of manufacturing tungsten filament at a low price was solved, and the tungsten filament bulb has been used ever since.
The biggest problem of light bulb is the sublimation of filament. The temperature is different because of the tiny resistance difference on the tungsten wire. Where the resistance is high, the temperature rises higher and the tungsten wire sublimates faster, which leads to the thinning of the tungsten wire and the further increase of the resistance. Finally, the tungsten wire burns out. Later, it was found that replacing vacuum with inert gas could slow down the sublimation of tungsten wire. Today, most light bulbs are filled with nitrogen, argon or krypton.
The life of modern incandescent lamps is generally about 1 1,000 hours. Why is it pear-shaped? This is because when the electric lamp is turned on, the tungsten wire in the bulb can reach a high temperature of about 2500℃, and some tungsten particles will evaporate from the surface of the tungsten wire. This light bulb is pear-shaped. When the inert gas in the bulb convects, most tungsten particles are swept away by the hot gas and deposited on the neck of the bulb, which can reduce the influence on the periphery and bottom of the bulb and maintain its brightness. So the bulb should be pear-shaped.