How the Light Bulb Changed History

How the Light Bulb Changed History — page 5 — technology that would preserve the materials in the bulb The next task was to identify a good filament During his first year of research Edison focused on platinum and learned it was not the best choice Edison came to believe the ideal filament could be made of carbon the primary element in living things because carbon could withstand the high heat generated by incandescence He carbonized various materials burning them until all that remained was the carbon itself and then shot an A CO2 electric current through each one Nothing stood out Some materials burned longer than others but nothing burned long enough Edison was more than a year into his experiments when his team tried a simple substance on October 22 1879 It had been in his house the whole time cotton thread The filament glowed and then it kept glowing Hour after hour after hour the carbonized cotton thread stayed lit Eventually what put out the A replica of Edison s incandescent lamp the first practical light bulb 10

How the Light Bulb Changed History — page 6 — light bulb was not fizzling filament but the bulb breaking By then it a had been lit more than 14 hours Two months later Edison was ready to unveil his new invention Shortly after Christmas and into the new year he gave demonstrations of his light bulb for reporters and the public He may have underestimated how much time it would take but he had succeeded in his goal to improve the light bulb CHOOSING CARBON With its resistance to high temperatures carbon seemed ideal for making a light bulb filament Plus it was readily available because it is a fundamental ingredient in plant life The team at Menlo Park believed filaments needed to be twisted and formed into spirals so a longer length of material could fit into a bulb They thought the shape would be more energy efficient by keeping more heat in the spiral But carbon was fragile and it was difficult to form these carbonized materials into spirals Edison s team experimented with straight lengths of carbon These carbon wires demonstrated a naturally high resistance and were stable within the vacuum lamp This simpler design proved successful in creating a working bulb The lamps Edison presented used cardboard filaments They were cheap but not optimal in terms of life The cotton thread had shown Edison carbon could work in his bulb Next he needed to find a more stable long lasting carbon material Simply Light Over time Edison steadily bettered his bulb Cardboard was an improvement lengthening the glow time to 100 hours Eventually 11

How the Light Bulb Changed History — page 7 — Edison settled on carbonized bamboo which was sturdier and extended the life of his bulb to 600 hours The technology itself was amazing but the revolutionary part was that Edison's bulb provided a kind of light people had never known BETTING ON BEARD As Edison searched for the perfect filament he actually tried hair from the beards of two men working in his lab The contest was enthusiastically followed Employee Francis Jehl later wrote a book about his experiences working for Edison He recalled Bets were placed with much gusto by the supporters of the two men and many arguments held over the rival merits of their beards In the end neither man had to shave his beard for the greater good the hairs were not the solution People were not accustomed to light arriving unaccompanied by sound smell and mess The gaslights that served many people hissed as the gas ran through the lines and the gas had a distinct odor The soot it gave off meant lamps had to be cleaned often Electric light did not come with the hissing sound of gas the smell of kerosene lanterns or the unreliability of flickering candles Nor did it require striking matches dipping wicks or refilling fuel When Edison demonstrated his new light to reporters they were struck by its low maintenance nature and all the qualities it lacked There is no flicker a Washington Post writer told his readers There is nothing between it and darkness It has no odor or color It is simply light Edison applied for a patent for his light bulb on November 1 1879 12

How the Light Bulb Changed History — page 8 — ANKLIN ANCHARD To the Honorable Commissioner of Patents Monr petitioner Micmas Clism Wuls Turkm the Man of Medveded hapthat LETTERS PATENT may be granted to her

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