How many filaments did edison use

Edison pushed hard on his research assistants, whom he more or less affectionately called "muckers. Inside a near-vacuum bulb, it stayed alight for more than half a day. The "three or four month" project had taken 14 months. Soon, the lab got a carbon-filament bulb to last 40 hours.

On New Year's Eve, 3, people visited the lab in Menlo Park to witness 40 electric light bulbs glowing merrily. Edison switched them on and off at will, dazzling and delighting his guests. These bulbs used carbonized cardboard. While actually a predecessor of the modern battery , Volta's glowing copper wire is also considered to be one of the earliest manifestations of incandescent lighting.

Not long after Volta presented his discovery of a continuous source of electricity to the Royal Society in London, Humphry Davy, an English chemist and inventor, produced the world's first electric lamp by connecting voltaic piles to charcoal electrodes.

Davy's invention was known as an electric arc lamp, named for the bright arc of light emitted between its two carbon rods.

While Davy's arc lamp was certainly an improvement on Volta's stand-alone piles, it still wasn't a very practical source of lighting. This rudimentary lamp burned out quickly and was much too bright for use in a home or workspace.

But the principles behind Davy's arc light were used throughout the s in the development of many other electric lamps and bulbs. In , British scientist Warren de la Rue developed an efficiently designed light bulb using a coiled platinum filament in place of copper, but the high cost of platinum kept the bulb from becoming a commercial success. And in , Englishman William Staite improved the longevity of conventional arc lamps by developing a clockwork mechanism that regulated the movement of the lamps' quick-to-erode carbon rods.

But the cost of the batteries used to power Staite's lamps put a damper on the inventor's commercial ventures. In , English chemist Joseph Swan tackled the cost-effectiveness problem of previous inventors and by he had developed a light bulb that used carbonized paper filaments in place of ones made of platinum.

Swan received a patent in the United Kingdom in , and in February he demonstrated a working lamp in a lecture in Newcastle, England, according to the Smithsonian Institution. Like earlier renditions of the light bulb, Swan's filaments were placed in a vacuum tube to minimize their exposure to oxygen , extending their lifespan. Unfortunately for Swan, the vacuum pumps of his day were not efficient as they are now, and while his prototype worked well for a demonstration, it was impractical in actual use.

Edison realized that the problem with Swan's design was the filament. A thin filament with high electrical resistance would make a lamp practical because it would require only a little current to make it glow.

It has the property of resisting the heat of the current of electricity, while at the same time it becomes incandescent, and gives out one of the most brilliant lights which the world has ever seen. The cost of preparing one of these little horse-shoes of carbon is about 1 cent, and the entire lamp will cost not more than 25 cents. And although his accomplishments spoke for themselves, Edison was equally prolific, and ambitious, in inventing myths to boost his reputation as a larger-than-life innovator, as a TIME profile notes.

For one thing, he often claimed to be entirely self-taught, having never attended a day of school. He also boasted of never needing more than three hours of sleep a night. That's a trick question really. In fact, Edison did not invent the light bulb. Various inventors dabbled in channeling electricity for light since the beginning of the 19th Century. Credit for the first electric light goes to the British chemist Humphry Davy who invented the Electric Arc lamp within the first decade of that century, though is more famous for the lamp that bears his name invented in Another English chemist, Warren de la Rue offered a design i n that relied on a coiled platinum filament in a vacuum tube.

It worked well. However the high cost of platinum rendered the bulb too expensive for mass production. In an English physicist named Joseph Wilson Swan used carbonized paper filaments for his bulb design, though it took yet another decade to make a working prototype, though its useful life made it not viable as a commercial product.

It took him until to developed a bulb with greater longevity that relied on treated cotton thread that also removed the problem of early bulb blackening. They used carbon rods held between electrodes in glass cylinders filled with nitrogen.

While the product worked, Canada is not really recognized as the cradle of electric bulbs. That's because even though Woodward obtained an American patent in , he wasn't able to launch his bulbs in the U.