The incandescent light bulb uses a glowing 
wire filament heated to white-hot by electrical resistance, to 
generate light (a process known as thermal radiation). The bulb 
is the glass enclosure which keeps the filament in a vacuum or 
low-pressure noble gas, or a halogen gas in the case of 
quartz-halogen lamps (see below). In Australia a light bulb 
is commonly called a light globe, most Australians don't realise 
that "globe" is not used in this sense outside Australia.
    
History of the light bulb

The invention of the light bulb is sometimes attributed to Thomas 
Alva Edison, who made contributions to its development and marketing, 
but today it is well-known that Heinrich Göbel built functional 
bulbs three decades earlier. Many others also contributed to 
the development of a truly practical device for the production 
of electrically generated lighting.

In 1801 Sir Humphry Davy, an English chemist, made platinum strips 
glow by passing an electric current through them, but the strips 
evaporated too quickly to make a useful lamp. In 1809 he created 
the first arc lamp, which he demonstrated to the Royal Institution 
of Great Britain in 1810, by creating a small but blinding arc 
between two charcoal rods connected to a battery.

In 1820 a British scientist Warren De la Rue enclosed a platinum 
coil in an evacuated tube and passed an electric current through 
it. The design was based on the concept that the high melting 
point of platinum would allow it to operate at high temperatures 
and that the evacuated chamber would contain less gas particles 
to react with the platinum, improving its longevity. Although it 
was an efficient design, the cost of the platinum made it 
impractical for commercial use.

In 1835 James Bowman Lindsay demonstrated a constant electric 
light at a public meeting in Dundee. He stated that he could 
"read a book at a distance of one and a half feet". However 
having perfected the device, to his own satisfaction, he turned 
to the problem of wireless telegraphy and did not develop the 
electric light any further.

In 1841 Frederick de Moleyns of England was granted the first 
patent for an incandescent lamp, with a design using powdered 
charcoal heated between two platinum wires.

In 1854, the German inventor Heinrich Göbel developed the 
first 'modern' light bulb: a carbonised bamboo filament, in 
a vacuum bottle to prevent oxidation. In the following five 
years he developed what many call the first practical light 
bulb. His lamps lasted for up to 400 hours. He did not 
immediately apply for a patent, but his priority was 
established in 1893.

Joseph Wilson Swan (1828-1914) was a physicist and chemist 
born in Sunderland, England. In 1850 he began working with 
carbonised paper filaments in an evacuated glass bulb. By 
1860 he was able to demonstrate a working device but lack 
of a good vacuum and an adequate supply of electricity 
resulted in a short lifetime for the bulb and inefficient 
light. By the mid-1870s better pumps became available, and 
Swan returned to his experiments. Swan received a British 
patent for his device in 1878. Swan reported success to 
the Newcastle Chemical Society and at a lecture in 
Newcastle in February 1879 he demonstrated a working lamp 
that utilised a carbon fibre filament. The most significant 
feature of Swan's lamp was that there was little residual 
oxygen in the vacuum tube to ignite the filament, thus 
allowing the filament to glow almost white-hot without 
catching fire. From this year he began installing light 
bulbs in homes and landmarks in England and by the early 
1880s had started his own company.

Across the Atlantic, parallel developments were also taking 
place. On July 24, 1874 a Canadian patent was filed for the 
Woodward and Evan's Light by a Toronto medical electrician 
named Henry Woodward and a colleague Mathew Evans, who was 
described in the patent as a "Gentleman" but in reality a 
hotel keeper. They built their lamp with a shaped rod of 
carbon held between electrodes in a glass bulb filled with 
nitrogen. Woodward and Evans found it impossible to raise 
financial support for the development of their invention 
and in 1875 Woodward sold a share of their Canadian patent 
to Thomas Edison.

Edison purchased the Woodward and Evans patent and had a 
team of developers search for an alternative filament 
material. Eventually he used a carbon filament that burned 
for forty hours (first successful test was on October 21, 
1879; it lasted 13.5 hours). Edison continued to improve 
their design. By 1880 he had a device that could last for 
over 1200 hours using a bamboo-derived filament, longer 
than the 400 hours of Heinrich Goebel's earlier light bulb.

In January 1882, Lewis Latimer received a patent for the 
"Process of Manufacturing Carbons," an improved method 
for the production of light bulb filaments which yielded 
longer lasting bulbs than Edison's technique.

In Britain, Swan took Edison to court for patent infringement. 
Edison lost and as part of the settlement, Edison was forced 
to take Swan in as a partner in his British electric works. 
The company was called the Edison and Swan United Electric 
Company. Eventually, Edison acquired all of Swan's interest 
in the company. Swan sold his United States patent rights 
to the Brush Electric Company in June 1882.

The United States Patent Office had ruled on October 8, 1883 
that Edison's patents were based on the prior art of 
William Sawyer and were invalid. Litigation continued 
for a number of years. Eventually on October 6, 1889, a 
judge ruled that Edison's electric light improvement 
claim for "a filament of carbon of high resistance" was 
valid. Research exposed in "A Streak of Luck" by Robert 
Conot (1979), shows that Edison and his attorneys hid 
significant information from the judge. They cut out the 
October 7-21, 1879 section of a notebook that the judge 
might have determined showed that they were simply extending 
Sawyer's (or Swan's) work with carbon "burners" or "rods" 
in an evacuated glass bulb.

Edison and his team did not find a commercially workable 
filament (bamboo) until more than 6 months after Edison 
filed the patent application. The weak and short lived 
(40-150 hours) carbon filament was eventually superseded 
by the tungsten filament. In 1903 Willis Whitnew invented 
a filament that would not blacken the inside of a light 
bulb. It was a metal-coated carbon filament. In 1906, the 
General Electric Company was the first to patent a method 
of making tungsten filaments for use in incandescent 
lightbulbs. The filaments were costly, but by 1910 William 
David Coolidge (1873-1975) had invented an improved method 
of making tungsten filaments. The tungsten filament 
outlasted all other types of filaments and Coolidge made 
the costs practical.

One of the major problems of the standard electric light 
bulb is evaporation of the filament. The inevitable 
variations in resistivity along the filament cause 
nonuniform heating, with ‘hot spots’ forming at higher 
resistivity. Thinning by evaporation increases resistivity. 
But hot spots evaporate faster, increasing their resistivity 
faster—a positive feedback which ends in the familiar tiny 
gap in an otherwise healthy-looking filament. Irving 
Langmuir suggested that an inert gas, instead of vaccuum, 
would retard evaporation and still avoid combustion, and 
so ordinary incandescent light bulbs are now filled with 
nitrogen, argon, or krypton.

A typical filament light bulb lasts about 1000 hours.