Fleming, John Ambrose

Sir John Ambrose Fleming was born on November 29, in 1849. He was an English electrical engineer and physicist who invented the first thermionic valve or vacuum tube, designed the radio transmitter with which the first transatlantic radio transmission was made, and also established the right-hand rule used in physics.

John Ambrose Fleming educated at Lancaster Royal Grammar School, University College School, London, and then University College London, where he obtained a BSc in 1870. He entered St John's College, Cambridge in 1877, gaining a DSc from the University of London in 1879 and a BA from Cambridge in 1881.

He went on to lecture at several universities including the University of Cambridge, University College Nottingham, and University College London, where he was the first professor of electrical engineering. He was also a consultant to the Marconi Wireless Telegraph Company, Swan Company, Ferranti, Edison Telephone, and later the Edison Electric Light Company. In 1892, Fleming presented an important paper on electrical transformer theory to the Institution of Electrical Engineers in London.

In 1899 Guglielmo Marconi, the inventor of radiotelegraphy, decided to attempt transatlantic radio communication. This would require a scale-up in power from the small 200–400 watt transmitters Marconi had used up to then. He contracted Fleming, an expert in power engineering, to design the radio transmitter. Fleming designed the world's first large radio transmitter, a complicated spark transmitter powered by a 25 kW alternator driven by a combustion engine, built at Poldhu in Cornwall, UK, which transmitted the first radio transmission across the Atlantic on 12 December 1901.

In 1904, working for the Marconi company to improve transatlantic radio reception, Fleming invented the first thermionic vacuum tube, the two-electrode diode, which he called the oscillation valve, for which he received a patent on 16 November. It became known as the Fleming valve.

Fleming also contributed in the fields of photometry, electronics, wireless telegraphy (radio), and electrical measurements. He coined the term power factor to describe the true power flowing in an AC power system.

Sir John Ambrose Fleming died on April 18, in 1945 at the age of 95.

Citing www.wikipedia.org