History of the Incandescent Light Bulb
Like all revolutionary inventions, the very first light bulb too was developed after a series of improvements had been made over the ideas generated by earlier inventors. So light bulbs in some rudimentary form existed before Thomas Alva Edison patented his light bulb, the one that resembles the lights used in commercial spaces today.
The Invention of the Incandescent Lamp
The seeds of the light bulb lie in the development of the incandescent lamp. In 1809, Humphrey Davy used a high-power battery to generate electric current between two strips of charcoal. The high amount of heat generated by the current flowing through the charcoal strips made them glow. This was the carbon arc lamp.
In 1820, Warren de la Rue attempted to invent the very first incandescent lamp. He inserted a platinum filament inside a partially vacuumed glass tube and channeled electric current through it. The high heat generated made the metal glow and produce light. Rue used platinum because the metal’s high melting point prevented it from disintegrating at high temperatures. He used a partially vacuumed tube to minimize the chances of gas particles reacting with the heated metal. Rue’s measure ensured that the platinum was stable and lasted a long time. An illustration of Warren de la Rue’s incandescent lamp is shown below.
His idea was functionally sound but was not commercially feasible because of the prohibitive cost of using platinum on a large scale.
The Challenge of Developing a Cost-Effective Incandescent Light Bulb
Warren de la Rue influenced many other inventors and scientists to strive to create a more practically feasible version of his platinum-filament incandescent bulb. Throughout the 1800s, William Robert Grove, W.E. Staite, John Daper, Frederik de Moleyns, Edward G. Shepherd, John T. Way, C. de Chagny, and Heinrich Göbel tried their hands at developing a practical light bulb.
They had to overcome one challenge—create a cost-efficient filament that remained stable even at high temperatures and lasted long enough to be commercially viable. In the process, they experimented with many different metals with high melting points by placing them inside partially or wholly vacuumed chambers and tubes filed with inert gases that do not react with metal.
In 1850, Edward Shepherd invented an incandescent arc lamp containing a charcoal filament. In the same year, Joseph Wilson Swan started his work on incandescent lamps using carbonized paper filaments. In 1854, Heinrich Göbel made a light bulb using a carbonized bamboo filament. But all these light bulbs did not last long enough till in 1878, Joseph Wilson Swan used a carbon fiber filament made from cotton inside his light bulb that went on to last 13.5 hours. Swan is regarded as the first person to make a practical and long-lasting light bulb.
The Light Bulb of Thomas Alva Edison
Thomas Alva Edison bettered the efforts of Joseph Wilson Swan in 1879 by inventing a light bulb that lasted forty hours. He used a carbon filament and placed it inside an oxygen-less glass bulb. He continued to work on his model to better the design, and in 1880, produced a filament from bamboo that could last up to 1,200 hours. Edison used this design for a light bulb for the next 10 years. However, he continued to work on other improvements in the design of the light bulb. For instance, he designed a vacuum pump that could remove all air from inside a glass bulb. He also developed the Edison screw that has now become the accepted standard for socket fittings on light bulbs.
The Legacy of Edison’s Light Bulb
Scientists and inventors had realized back in the 1800s that the efficiency of a light bulb depended on creating an environment where the filament could heat to high temperatures without disintegrating and leading to a loss of heat. Carbon has a very high melting point of 6,510oF, but it evaporates at high temperatures. This reduced the longevity of light bulbs with carbon filaments. Inventors tried to increase the longevity of light bulbs by heating the filament only at low temperatures. But this reduced the incandescence of the bulb. So the hunt was on for filaments that could be heated to produce bright glows and lasted long too.
In 1898, Karl Auer used osmium with a melting point of 4,890oF, and in 1903, Siemens used tantalum with a melting point of 5,425oF as the filament metals. These metals could be heated to high temperatures without evaporating. Using these metals, light bulbs emitted brighter glows and lasted a respectable amount of time as well.
The Era of the Tungsten Light Bulbs
The development of the modern tungsten filament incandescent light bulb can be attributed to the research work carried out by the General Electric Company and William David Coolidge. In 1903, the General Electric Company used ductile tungsten filament. Tungsten has a melting point of 6,170oF and low evaporation rates at high temperatures. It can be heated to white hot temperatures and provide bright glows.
In 1910, Coolidge devised a way to make tungsten filaments at lower costs and thus made light bulbs affordable. The tungsten filament light bulb was improved a notch by Irving Langmuir. In 1913, Langmuir introduced nitrogen, an inert gas, inside the light bulb to increase the latter's efficiency. The introduction of inert gases reduced evaporation of the filament metal and increased filament stability.
How Halogen Gas Makes Incandescent Bulbs More Efficient
Halogen light bulb is a specific type of incandescent lamp, and uses halogen gas (chlorine) inside the bulb. The first halogen lamp was patented in 1882. However, General Electric patented the first halogen lamp that used iodine in 1959. When tungsten evaporates, it reacts with the halogen gas to form halide. Halide does not form a dark coating on the inner surface of the bulb and so reduces blackening of the device. On the other hand, halide at high temperatures disintegrates into tungsten and halogen. The tungsten returns to the filament while the halogen fills up the insides of the bulb. This unique tungsten-halogen cycle gives more stability and longevity to incandescent bulbs.
The Age of the Energy-Efficient Light Bulbs
The incandescent light bulb was, by no means, an energy-efficient device. It could convert only 10 percent of the energy supplied to it into light. So in search of energy efficiency, scientists started experimenting with discharge lamps—a 19th-century technology invented by Heinrich Geissler and Julius Plücker where electric current is conducted through a fully vacuumed glass tube. Discharge lamps were the precursors of neon lights, low-pressure sodium lamps, and fluorescent light bulbs.
Experimentation with fluorescent lights continued throughout the first half of the 1900s, starting with Peter Cooper Hewitt's invention. He conducted electric current through mercury vapor and used a ballast to control the flow of the current. His product was more energy-efficient than incandescent bulbs.
LEDs: The Future of Light Bulbs
Nick Holonyak, Jr. invented the first LED (light-emitting diode) light in 1962 during his stint with General Electric. In the LED technology, a semiconductor is used to convert electricity to light. Research and development work on LED lights is continuing still today. LED lights are the most energy-efficient lighting devices right now (but have higher sticker costs than a normal incandescent light bulb) in the market and are used extensively in the commercial and manufacturing areas to minimize operational costs.