So Edison began to experiment with filament materials. With great perseverance and patience, Edison experimented with 1600 materials and used carbon strips, platinum wires, ruthenium, chromium and other metals as filaments, all of which ended in failure. Edison didn't flinch in the face of failure and some people's cynicism. After 13 months' efforts, Edison tried more than 6,000 kinds of materials and more than 7,000 times. Finally, he found that cotton thread could be used as a filament and burned it for 45 hours. This is the first electric lamp with practical value. This day-1879101October 2 1 day was designated as the electric light invention day. After further experiments, Edison found that bamboo filaments are very effective and durable, and the light bulb can be lit for 1200 hours. From then on, electric lights began to enter the homes of ordinary people.
Later, people have been using this kind of light bulb with bamboo filaments. After decades, it was improved, that is, tungsten wire was used as the filament, and inert gas nitrogen or argon was filled into the bulb.
In this way, the life of the light bulb is prolonged a lot. This is the kind of light bulb we use now.