How long did it take to invent the light bulb?

Answer 1

Sir Humphrey Davy of the UK demonstrated the first incandescence light in 1812. It was very inefficient, using electrically heated strips of platinum to produce light. British inventor Frederick de Moleyns was awarded the first patent for an incandescent lamp in 1841. His lamp used powdered charcoal heated between two platinum wires as the source of light. The next major improvement was in 1878 by British scientist Sir Joseph Wilson Swan, using carbon filaments in a partial vacuum inside glass bulbs. American inventor Thomas Alva Edison independently discovered the same device a year later in 1879. The last major improvement was in 1911, 99 years after Sir Humphrey Davy made his demonstration, when a research group led by William David Coolidge, an American engineer working for General Electric, developed the present method of using tungsten filaments in incandescence light bulbs.