Thomas Edison focused on inventing an inexpensive and safe electric light bulb to replace gas lighting in 1878. After many experiments with different filament materials like platinum, he returned to using a carbon filament. The first carbon filament bulb lasted over 13 hours. Edison continued improving the design and was granted a patent for an electric lamp using a carbon filament in 1880. A few months later, Edison's team discovered that a carbonized bamboo filament could last over 1,200 hours, helping make the light bulb practical for widespread commercial use.

1. Thomas Edison
&
The Incandescent Light Bulb

2. Thomas Edison
• In his 84 years, Thomas
Edison acquired a record
number of 1,093 patents
(singly or jointly) and was
the driving force behind
such innovations as the
phonograph, the
incandescent light bulb
and one of the earliest
motion picture cameras.

3. First Attempts
In 1809, an English chemist,
Humphrey Davy, started the
journey to the invention of a
practical incandescent light
source. He used a high power
battery to induce currents
between two charcoal strips.
In 1820, Warren De la Rue made
the first known attempt to
produce an incandescent light
bulb. He enclosed a platinum
coil in an evacuated tube and
passed an electric current
through it. Although it was an
efficient design, the cost of the
platinum made it impractical for
commercial use.

4. Research & Development
• In 1878, Edison focused
on inventing a safe,
inexpensive electric light
to replace the gaslight--a
challenge that scientists
had been grappling with
for the last 50 years.
• Edison set up the Edison
Electric Light Company
and began research and
development.

5. The Carbon Filament
• After many experiments with
platinum and other metal
filaments, Edison returned to
a carbon filament. The first
successful test lasted 13.5
hours. Edison continued to
improve this design and by
November 4, 1879, filed for a
U.S. (granted on January
27, 1880) for an electric
lamp using "a carbon
filament or strip coiled and
connected to platina contact
wires".

6. Bamboo
• A few months after receiving
his patent Edison and his
team discovered a
carbonized bamboo
filament that could last over
1,200 hours. The idea of
using this raw material
originated from Edison's
examination of a few threads
from a bamboo fishing pole
while relaxing on the shore of
Battle Lake in the present-
day state of Wyoming.

7. "We will make electricity so cheap that only
the rich will burn candles.”
-Thomas Edison