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The Birth of Electronics
May 23rd, 2010
Thermionic emission is the discharge of electrons from a hot metal cathode into a vacuum. This effect is the fundamental basis for the development of electronics as we know it today.
The effect was initially discovered in 1873 when Frederick Guthrie (professor at the Royal School of Mines and one of the founders of the Physical Society of London – now the Institute of Physics) found that a piece of iron with a negative charge would lose that charge when heated – but would not if the iron was positively charged. Nothing directly came of this discovery…
Until ... Thomas Edison re-discovered the effect in 1883 during work on electric lights and the phenomena was named the "Edison Effect" although Edison saw no use for this effect and moved on to other things - after he filed for a patent for a voltage regulating device which was granted in 1884.
But nothing in particular came out of Edison's work either.(US Patent 307,031).
In the meantime ...
Dr JJ Thomson proved that the atom was not indivisible by demonstrating that electrons were particles in 1897. The term "thermionic emission" was introduced by Owen Richardson - whose PhD adviser was Dr Thomson.
Meanwhile ...
J Ambrose Fleming - the originator of the "right-hand rule" - attended the Royal College of Science at University College in London where his doctoral adviser was Dr Guthrie. He consulted for the Edison Electric Company throughout the 1880s and moved on to the Marconi Wireless Telegraph Company.
There was some degree of doubt regarding the validity of Marconi's transmission experiments in 1901 which led Dr Fleming to conduct experiments regarding wireless receivers. He found that the Edison Effect was capable of converting alternating signals to pass in only one direction which enhanced the reception of the transmitted signal. Further refinement led to US Patent 803,684 in 1904.
The first...