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J J Thomson

JJ Thomson is intimately connected with the concept of the electron. He is credited with the discovery of electrons. More accurately, he proposed and demonstrated that cathode rays are not massless radiation, but were actually made of small charged particles which he called 'corpuscles'. 
 
Joseph John (J. J.) Thomson was born in England in 1856 and was going to be an engineer. However, after the death of his father (when Thomson was 16), his mother couldn't afford the large apprenticeship fee. So he stayed at college in Manchester and, some years later, won a scholarship to Cambridge University where he worked for the rest of his life. 
 
At the age of 28, Thomson was given the post of Cavendish Professor in the Physics Department at Cambridge University. He was in charge of the laboratory despite, as his assistant put it, "being very awkward with his fingers" and being discouraged from handling the instruments. He was, however, inspired with his designs for apparatus and interpretations of experimental results. 
 
Thomson's work on gas discharges and cathode rays led, in 1897, to his discovery of the electron - his interpretation of the results of deflecting cathode rays. 
 
A theorist as well as an experimenter, Thomson described the plum-pudding model of atomic structure, in which electrons were like negative 'plums' embedded in a 'pudding' of positive matter. This was a first step on the road to the current model of the atom (Based on the J J Thomson entry at physics.org).