British scientists David and Faraday invented the arc lamp.
Tungsten is hard and brittle, making it difficult to process. When the current passes through the tungsten wire and is heated to a certain temperature, the resistance value of the tungsten wire also increases to a certain value (generally, the resistance value of metal wire increases as the temperature increases). At normal temperature, the resistance of this object should be 1370℃-2000℃, but when the cross-sectional area length of the tungsten wire changes, the resistance value will change. In 1909, Coolidge invented the tungsten filament processing technology, which played a decisive role in the production and promotion of incandescent light bulbs. Its basic principles are still used today.