The History of Light Bulbs

One of the first electrical effects used to produce light was incandescence. This is emission of light from a heated body. First electrical incandescent light was created in 1802 by British chemist and inventor Sir Humphry Davy. He used platinum strip through which he passed electric current. Platinum was chosen because it has a very high melting point. This incandescent light had two major flaws which prevented practical applications. The light was not bright enough and it only lasted for a short time. But this experiment is important because the first practical incandescent bulbs appeared almost 80 years later.

During the 19th century many experimenters tried various materials and designs. It was British scientist Warren de la Rue who came to the idea to put platinum filament into a vacuum tube. Vacuum is essential because it prevents air molecules to react with the filament which reduces its life. Unfortunately this invention was still not practical because the high cost of platinum. Many patents for incandescent bulbs were granted for various implementations including the one with carbon filament. Because many rivals were working on similar projects some tried to bypass patents which lead also to few law suits.

Many technical problems had to be solved in order to make a bulb for commercial production. High vacuum is essential for long operation. Until 1870s there were no pumps which could make a satisfactory high vacuum for light bulbs. With the use of Sprengel pump it was possible to easily achieve required vacuum. This pump was one of the key factors that contributed to the success of incandescent light bulbs. The material used for the filament is also very important. It must produce bright light, have long life and should be cheap enough for mass production. Many bulbs at that time used carbon filament which was far from the ideal material. In 1904 tungsten filament was patented and Hungarian company Tungsram started production. It was also found that if the bulb is filled with inert gas it has higher luminosity and the effect of blackening is reduced.

Today this kind of bulbs is produced in millions. Unfortunately, cheap production is the only advantage of incandescent bulbs. They are very inefficient--only few percent of the electrical energy is converted into light, the rest is dissipated as heat. There are some attempts to increase the efficiency of incandescent lamps but this will not change the overall picture of inefficient lighting. Therefore, many countries have taken steps to replace them with more efficient compact fluorescent lamps.

Most bulbs create light which is slightly colored. But there are also full spectrum bulbs which can reproduce natural sunlight. Such bulbs are used in environments where accurate color reproduction is important. But full-spectrum light bulbs can also be used at home. For many people natural white light creates a very pleasant living environment.