During the development process, Thomas Alva Edison carefully analyzed the gas lamps and arc lamps of the time. His main focus was to find a heat-resistant material. The current burns it to a white-hot level and emits blazing light without breaking or melting. He accidentally discovered that cotton threads burned to ashes in the air, while carbon cotton threads emitted blazing light when placed in a treated glass ball. Unfortunately, the light only lasted a few minutes before disappearing. He mistakenly gave up on this experiment and instead tried 1,600 different heat-resistant materials such as cesium, nickel, platinum (platinum), and platinum-iridium alloys, with little success.
Thomas Alva Edison returned to the study of carbon. In October of that year, he tested a carbon rod with a length of 20 cm and a diameter of 0.15 cm. Its heat resistance reached 5.5 hours. He continued to improve the carbonization method and air extraction treatment.
On October 21, 1879, he used a carbonized cotton thread with a diameter of 0.025 cm as a filament. The light emitted was bright and stable. It used an illumination of 4 candles for 1 hour. , 2 hours... It stayed on for a full 45 hours, after more than a year of hard work and thousands of tests. The long-awaited electric light was finally born.
In November of the same year, after Thomas Alva Edison switched to carbonized cardboard to greatly improve the life of the electric light, the manufacturer couldn't wait to put it into production. On New Year's Eve 1880, 3,000 people took to the streets of New York to see this new invention. Success did not stop Thomas Alva Edison. The next year, he created a moso bamboo filament lamp that could last for 1,200 hours. It was not until 1904 that the Austrians invented a tungsten lamp that was three times more powerful than the moso bamboo lamp, and the former was replaced. Tungsten lamps have been in use since 1907.