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Sir Joseph John (J. J.) Thomson

By Anne Marie Helmenstine, Ph.D., About.com

Sir Joseph John (J. J.) Thomson

Sir Joseph John (J. J.) Thomson

Born: December 18, 1856, Cheetham Hill, near Manchester, England
Died: August 30, 1940, Cambridge, Cambridgeshire, England
Claim to Fame: Discovered the electron.
Notable Awards: Nobel Prize in Physics (1906)
Knighted (1908)
Summary: Many scientists studied the electric discharge of a cathode ray tube. It was Thomson's interpretation that was important. He took the deflection of the rays by the magnets and charged plates as evidence of "bodies much smaller than atoms". Thomson calculated these bodies had a large charge to mass ratio and he estimated the value of the charge itself. In 1904, Thomson proposed a model of the atom as a sphere of positive matter with electrons positioned based on electrostatic forces.

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