Born August 30, 1940

J.J Thomson

English Physicist

Cheetham Hill, Manchester, United Kingdom

Research

In 1894, Thomson began studying cathode rays, which are glowing beams of light that follow an electrical discharge in a high-vacuum tube. It was a popular research topic among physicists at the time because the nature of cathode rays was unclear.

In 1906, Thomson began studying positively charged ions, or positive rays. This led to one of his other famous discoveries in 1912, when he channeled a stream of ionized neon through a magnetic and an electric field and used deflection techniques to measure the charge to mass ratio.

In doing so, he discovered that neon was composed of two different kinds of atoms, and proved the existence of isotopes in a stable element. This was the first use of mass spectrometry.