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'Evolution of artificial lighting' - research paper


Fortnight 1 / -  
Mar 2, 2012   #1
I had to write a research paper on Evolution of artificial lighting. This is what I came up with. Any feedback is appreciated. Thanks :)

Since the dawn of time, light has played an enormously critical role in the evolution of humans, animals and even plants. When humans discovered fire, it did more than just produce new ways of creating and destroying things, it created a new way of life for them. With fire, suddenly they could light up their surroundings after the sun had gone down. With fire, they could explore new areas of the world that they had not been able to explore before. With fire, they could locate each other in the night. With fire, they could do countless things previously thought impossible. Fire changed everything. But sadly, it has its limitations. As a sentient species we are constantly trying to find new ways around current limitations in order to not only survive, but thrive. And so, the need for a new source of light was established, and the race for the electric light began.

The incandescent light bulb was the first electrical light. Sir Humphrey Davy was an English chemist who was very experienced with electricity. In 1809, he found that by hooking two charcoal rods up to a high power battery, and arcing electricity between them, one could create light. This experiment was the first "arc lamp". There was no bulb, but it was surrounded by an iron mesh, and the problem Davy faced was that the charcoal tended to get very hot and burn away in a short time. In 1820 another scientist named Warren De la Rue ran electricity through a coil of platinum inside an evacuated tube, and thus created another electrical light source. This one was much brighter and more efficient than Davy's but the high cost of platinum made this design very uneconomical. The reasons why Warren De la Rue chose this expensive design were that platinum can withstand very high temperatures before melting, and the evacuated tube meant that there were only a small number of gas particles present to react with the platinum, which would extend its lifespan. In 1835, a Scottish inventor named James Bowman Lindsay created a prototype of an incandescent bulb and demonstrated it to various institutions. Unfortunately he did not feel the need to further his research or publish his works so not much is known about this particular light bulb. In 1841 Frederick de Moleyns was given the first patent for an incandescent light bulb. His design used a charcoal powder connecting two platinum wires inside a vacuum bulb. In 1845, an American man named John Starr acquired a patent for his incandescent light bulb, which also used carbon filaments. He died a short while after the patent came through though and not so not much about his invention is known. In 1850 a British physicist and chemist named Joseph Swan started working on a new design for incandescent light bulbs. This design used carbonized paper filaments instead of charcoal, as well as being contained in a partial vacuum. Swan was hindered by lack of a good vacuum and an inadequate power source and so in 1860 when he demonstrated his device, it was very inefficient and had a woefully short lifetime. In 1875, a man named Herman Sprengel came up with a solution to the vacuum problem. He created a "mercury vacuum pump" which worked by trapping bubbles of air in between drops of mercury in order to pump the air out of a container and create a vacuum. This invention made the creation of a practical and efficient light bulb possible. Joseph Swan returned with a new carbonized thread as a filament for his light bulb, and continued his research into artificial lighting in 1775 after the creation of the mercury vacuum pump. This new vacuum pump allowed him to create a much better vacuum inside the bulb which greatly decreased the amount of oxygen inside the bulb. Less oxygen meant a much lower likelihood that the filament would burst into flames when it grew hot. Swan's new light bulb was able to produce a much brighter glow at a much hotter temperature than before, created a more practical light source. His light bulb lasted for about 13.5 hours, as he successfully demonstrated it various times in 1878 and 1879, and then turned his studies towards a better filament. He created a new filament out of treated cotton and obtained a patent for it in 1880. Swan then started selling his light bulb to the general public and soon he had whole buildings being lit solely by his invention.

Across the seas, an American scientist named Thomas Edison was working on improving the designs of those before him. Finally, in 1879, after countless experiments, Edison also found that by using carbonized paper filaments you can create a very efficient light bulb. Edison's lasted for a whole 15 hours before burning out. After exhausting about 6,000 different plant sources for an even more efficient filament, Edison discovered that carbonized bamboo could last a whopping 1,200 hours. Edison's work on the light bulb was so similar to Swan's, that in order to avoid a lawsuit, the two of them created a joint company called Ediswan under the conditions that Edison could have the rights to his light bulbs in the United States, and Swan would keep his patent rights in Britain. Eventually Edison took over the whole company and Swan sold his patent rights to another company in 1882. Throughout the next 50 years a few other scientists tried experimenting with new filaments, but no important improvements were made until 1904 a Hungarian scientist named Sandor Just received a patent for his work in creating a filament out of tungsten. This new filament glowed brighter and longer than the carbon ones and so it was quickly adopted by many companies for their products. In 1913, Irving Langmuir found that filling the glass bulb with an inert gas increased the brightness of the light bulb, as well as decreasing the amount of blackening on the inside of the bulb. Many manufacturers used argon for this, but in 1930, another Hungarian scientist by the name of Imre Brody filled his light bulbs with krypton gas, using a process that he created to obtain the gas from the air. This resulted in a very economical bulb. By 1964, the cost of manufacturing and running incandescent light bulbs had gone down exponentially, compared to what the price was when Edison was still researching them.

Incandescent light bulbs may have revolutionized the way we live, but they are not without fault. For example, even after all the improvements in efficiency that were made, 90% of the power that goes into the bulb is emitted as heat. In response to this, Peter Cooper Hewitt, in the late1890's, created a "discharge lamp" that was in a mercury vapor. This was the first fluorescent light bulb. It had a much higher efficiency than its incandescent counterparts, but it emitted a weird bluish-green color light, which restricted it to very specific uses. In 1927 Edmund Germer, Friedrich Meyer, and Hans Spanner patented a "high-pressure vapor lamp" which changed the color of the light that was emitted to something more normal. In 1976, Edward Hammer created the helical bulb (three-dimensional spiral) in response to an oil crisis. His bulb met the requirements, but General Electric would have had to pay around 25 million dollars to outfit their factories to produce this bulb and so his invention was put into storage for the time being. Finally, in 1980, a company called Phillips created a compact fluorescent light bulb (CFL) with the same screw in socket that the incandescents had, effectively creating a substitute. In addition, CFLs use from about one quarter to one third of the amount of power and have from eight to fifteen times the lifespan of comparable incandescents. The problem with them is that they use mercury, which is poisonous and has to be disposed of properly.

Incandescent bulbs work by electrically heating a filament. It will become so hot that it begins to glow. When this happens, the filament emits light. Nowadays the filaments are made out of Tungsten. Oxygen would react in the extreme heat of the filament and burn it up, so it is necessary to isolate the filament from oxygen by placing it in a bulb. The bulb is then filled with inert gases (gases that don't react) and so there is a very small likelihood (if any) that the filament will burn. The result is a light bulb that produces light and a lot of heat.

Fluorescent light bulbs are far more complex than incandescents, as well as being more efficient. They use tubes filled with argon and a tiny bit of liquid mercury. The inside of the tubes is coated with phosphorous. When electricity runs through the electrodes in a fluorescent light, it causes free electrons to travel from one end of the tube to the electrode at the other end. This vaporizes some of the mercury. Electrons and ions collide with the mercury atoms and release ultraviolet photons. This isn't good enough because we can't see ultraviolet light, this is where the phosphorous coating comes into play. The phosphor absorbs the ultraviolet light and radiates it back out as light visible to us. In incandescent light bulbs, ultraviolet light is wasted as heat, but in fluorescent light bulbs, it is turned into visible light, which is why they are so much more efficient than the incandescents. Because of the way atoms become ionized, early techniques for turning these light bulbs on would take as long as a minute, but now we can instantly turn them on by electronically controlling the electrical current in the electrodes.

The structure of the atoms dictates what kind of photon is created, and that means that different types of bulbs will appear to give off different color light. People tend to lean towards incandescent light bulbs for their homes because they give off much more light in the red end of the spectrum and so they appear "warmer". Fluorescent light bulbs give off more of a blue spectrum of light and appear "cooler".

In conclusion, I think we should switch over to fluorescent lighting because it would help save a lot of energy that is currently being wasted by using incandescent light bulbs. With proper disposal techniques and smart placement, fluorescent lighting could help alleviate some of the pressure that is put on the electrical systems in use today.

Jennyflower81 - / 690 96  
Mar 6, 2012   #2
Since the dawn of time, light has played aenormously critical role in the evolution of humans, animals and even plants.

With fire, they could do countless things previously thought to be impossible. Fire changed everything.

There was no bulb, but instead it was surrounded by an iron mesh. andThe problem Davy faced was that the charcoal tended to get very hot and burn away in a short period of time.

This one was much brighter and more efficient than Davy's, but this design was not economicaldue to the high cost of platinum. made this design very uneconomical.


He died a short while after the patent came through though and not so not much about his invention is known.
Re-word this sentence, it sounds confusing.

Across the seas
Overseas

The bulb is then filled with inert gases (gases that don't react) and so there is a very small likelihood (if any)which makes it unlikely that the filament will burn.


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