An electric bulb is a lamp that uses a resistor to heat a fine wire (usually tungsten wire in modern times) to incandescence through power on. So why does the light bulb shine? The following is the principle of light emitting of electric bulb, which I sorted out. Welcome to read and refer to.
Principle of light emission of electric bulb
The main device that can emit light in an electric bulb is the filament, which is wound with fine tungsten filament. In the electric light bulb made of glass, the air is pumped out, and non combustible gases such as nitrogen and argon are filled in, and then sealed. When the current is transmitted from the wire to the filament, due to the very high resistance of the filament, high heat will be generated, and light will be generated when the heat reaches a certain degree.
Historical origin of light bulb
It is generally believed that the electric lamp was invented by American Thomas Edison. Many people in the United States had made the same contribution to the electric bulb decades before Hein ö gordig invented it. In 1801, British chemist David electrified platinum wire to emit light. He also invented the electric candle in 1810, which was illuminated by an arc between two carbon rods. In 1854, Henry Goebbels used a carbonized bamboo wire and put it under a vacuum glass bottle to make electricity and light. His invention today appears to be the first incandescent lamp with practical utility. The bulb he tested at that time could last 400 hours, but he didn't apply for a design patent in time.
In 1850, the Englishman Joseph Wilson Swan began to study electric lamps. In 1878, he obtained a British patent for the bulb powered by carbon wire under vacuum, and began to establish a company in Britain to install electric lamps in various families.
In 1874, two electrical technicians in Canada applied for an electric lamp patent. They fill the glass bubble with nitrogen and glow with electrified carbon rods. But they didn't have enough money to continue to develop the invention, so they sold the patent to Edison in 1875.
Edison bought the patent and tried to improve the filament. In 1879, he changed to carbon wire to make light bulbs, which 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 Britain was forced to make Swan a partner. But then Swan sold his rights and patents to Edison. In the United States, Edison's patent was also challenged. The U.S. 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 the use of tungsten instead of carbon as a filament. Then in 1906, General Electric invented a method to make tungsten wires for electric lamps. Finally, the method of cheap manufacturing tungsten wire has been solved, and tungsten wire electric bulbs have been used so far.
The biggest problem of electric bulb is the sublimation of filament. Because of the slight resistance difference on the tungsten wire, the temperature is different. Where the resistance is large, the temperature rises higher and the tungsten wire sublimates faster, resulting in the cycle of thinning the tungsten wire and further increasing the resistance; Finally, the tungsten wire was burnt out. Later, it was found that the sublimation of tungsten wire could be slowed down by replacing vacuum with inert gas. Most electric light bulbs today are filled with nitrogen, argon or krypton.
Modern incandescent lamps generally have a service life of about 1000 hours.