History of the Light Bulb

 

Early man knew the sun as his lightsource and when the sun set, he knew the moon and the stars. As his intelligence increased and he learned about the world in which he lived he bacame associated with fire. Fire could be used for warmth, cooking, protection, and light. Man lived with this for years, elaborating and improving the way the fire was created and burned for light, until the year of 1809 when one man, an English chemist by the name of Humphrey Davy began the search for a usable incandescent light source using electricity. Using a high powered battery to induce a current between two high powered strips he produced an intense incandescent light, which baceme known as the first arc lamp.

Although it was a first step it was not yet a practical light source. The first known attempt to make a actual bulb didn't come until 1920 when Warren De la Rue enclosed a coil of platinum wire in an evacuated tube and passed an electrical current through it. Although a platinum light bulb was not practical the idea behind his design was. A metal with a high melting point to achieve high temperature and thus bright light, as well as an evacuated tube that contained less particles to react with the metal and thus an elongated bulb life.

Throughout the next few decades scientists labored to create their "efficient" light bulb. Their main hurdle was finding a low cost, long lived, high temperature filament material that would glow with high intensity.

In 1879 two scientist, Joseph Wilson Swan and Thomas A Edison, had independent breakthroughs for a longer lasting incandecent bulb with their use of a carbon fiber filament derived from cotton. It lasted a maximum of 13.5 hours. In 1880 Edison also developed a filament derived from bamboo which lasted up to 1200 hours. This was good, but to create a truly efficient bulb something different was need to creae a filament with very high temperatures but without degeneration and loss of heat.

Many elements were experimented with, a few of the most popular which were carbon, osmium, and tantalum. But the first of the light bulbs as we know them today was not created until between 1906-1910 with the invention of of ductile tungsten. The General Electric Company, along with William Coolidge realized the many favorable properties of tungsten such as its high melting temperature, its low deterioration (less than 1/100th that of carbon), its tensile strength greater than steel, as well as the fact that it glows white hot, creating a bright light. These early tungsten filaments still sublimed (or evaporated) too quickly at such high temperatures and as they did they also coated the inside of the bulb with a thin black powder decreasing light output.

Later, such inert gasses as nitrogen and argon were added inside bulb to decrease tungsten sublimation. Although this reduced sublimation and increasing bulb life, the inert gas also carried heat away from the filament, decreasing temperature and brightness. It was found that winding the tungsten filament into a finely wound coil reduced heat loss, thus allowing the bulb to operate as desired and giving us our modern day incandescent light bulb.