A Brief History of Light

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A Brief History of Light
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1745 1784 Candles

• Half Pound of Candles Required to Light an
  Average Home for One Night
• Benjamin Franklin Candlelight is smoky,
  unwholesome, and enormously expensive.

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1784 1838 Lanterns

• 1784 - Ami Agrand invents the Oil Fed Lantern
• 1787 - John Miles makes an affordable, adjustable
  lantern
• The average American did not have access to
  Lighting until the 1840s with commercial
  kerosene distribution.
• Burning gas inside buildings produces ammonia,
  sulfer, carbon dioxide, and consumes oxygen,
  causing illness .
• Gas is dangerous. It is very easy for a man to
  go to his hotel, blow out the gas and wake up
  dead in the morning

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1838 1878 Early Electric Lighting

• When heated to high temperatures, platinum,
  iridium, and carbon emit light (this is called
  incandescence).
• Beginning in 1838, inventors such as Frederick de
  Moleyns ran electric current through these
  materials in attempts to make lamps.
• However, incandescence was abandoned by 1860, as
  filaments would fall to pieces with minutes of
  reaching incandescence.
• The Arc Lamp, which produces light by voltaic
  arc, was developed in the late 19th century and
  was believed to be the future of artificial
  lighting. However, Arc lamps produced light that
  was far too intense for domestic use.

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Thomas Edison

• In the late 1870s, Thomas Edison took on the
  challenge of producing artificial light. When
  revealed we was going to attempt this by
  incandescence
• I cannot tell you what Edisons method may be,
  but . . . any system depending on incandescence
  will fail Silvanus Thompson
• Edisons activities are unworthy of the
  attention of practical or scientific men
  British Parliament

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Two Major Breakthroughs

• Within a year of experimentation, Edison made two
  breakthroughs that established incandescence as a
  viable light source
• 1. The Filament must burn in a vacuum
• - Edison noticed that, when sealed inside a glass
  bulb, a black deposit formed after the filament
  burned for several minutes. This deposit proved
  to be the same material as the filament. Edison
  concluded that the heated air inside the bulb
  wore down the filament and deposited it in the
  inside of the bulb. The deposit took longer to
  form and the filament lasted longer as air was
  pumped out of the bulb. The pressure in Edison's
  final bulb was less than 1 millionth of an
  atmosphere.

• The Filament Must be Pure
• - Edison observed a sample platinum
  filament that was heated to a temperature below
  incandescence and noticed the sample was cracked
  in innumerable placed. He concluded that his
  samples of platinum were impure, and contained
  pockets of air that violently escaped when the
  material was heated. He resolved this by slowly
  heating his filaments to incandescence prior to
  their use in a bulb. This allows the air pockets
  to escape in a non explosive manner.

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The Incandescent Lamp

• With the other aspects of the light bulb
  perfected, Edison only needed a proper filament.
  
• In 1879, Edison switched from metal filaments to
  carbon filaments. His approach in finding a
  carbon filament was rather non experimental, as
  he attempted to use carbonized forms nearly
  anything (such as his assistants beards).
  However, a carbonized form of bamboo proved to be
  the final filament.
• The final bulb consisted of a carbon coil
  suspended between
• two platinum leading wires (platinum expands at
  the same
• rate of glass when heated). This was a major
• breakthrough in artificial light, but one
  important problem
• remained

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How Do We Distribute Electric Lighting?
Series Circuit
Parallel Circuit
Why did no one else think of this? - No
one else is Edison - Sir William Thompson