The electron was discovered during experiments on passing electric current through gases in the discharge tube. Highly evacuated discharge tube becomes dark and a diffused spot is observed on the screen in front of the cathode. It indicated emission of invisible rays from the cathode which were named cathode rays.
In 1895, Jean Perin observed that under the influence of an electric field, the diffused spot on the screen shifted in the direction opposite to the field indicating that the cathode rays are the stream of negatively charged particles. As the charge can be possessed by mass, it was concluded that the cathode rays must possess mass. It also indicated that these charged particles existed as discrete entity. In 1874, G. Jhonstone Stoney experimentally demonstrated the existence of such charged particles. In 1891, he named this particle as ‘electron’.
J. J. Thomson conducted experiments of passing charge through the discharge tubes filled
with gases at low pressure. On reducing the pressure of gas in the discharge tube, Faraday
dark space and Crookes dark space were observed. Hertz, who experimentally proved the
existence of electromagnetic rays believed that electromagnetic rays are produced from
cathode. Julius Plucker discovered that magnetic field affects the cathode rays. Thomson
showed that the cathode rays in Hertz experiment were affected by electric field. This showed
that the cathode rays cannot be electromagnetic rays.
J. J. Thomson experimentally determined the ratio of charge to mass of an electron and found
it to be 1.8 * 10exp11 C / kg. Earlier, the ratio of charge to mass was determined for different
ions with the experiments of electrolysis. This ratio for hydrogen ion was 9.6 * 10exp7 C / kg.
Hence, Thomson concluded that the mass of electron should be 10 power- 3 to 10 power - 4 times the mass of hydrogen ion. Thomson called these particles ( electrons ) as primordial particles.
In 1895, Jean Perin observed that under the influence of an electric field, the diffused spot on the screen shifted in the direction opposite to the field indicating that the cathode rays are the stream of negatively charged particles. As the charge can be possessed by mass, it was concluded that the cathode rays must possess mass. It also indicated that these charged particles existed as discrete entity. In 1874, G. Jhonstone Stoney experimentally demonstrated the existence of such charged particles. In 1891, he named this particle as ‘electron’.
J. J. Thomson conducted experiments of passing charge through the discharge tubes filled
with gases at low pressure. On reducing the pressure of gas in the discharge tube, Faraday
dark space and Crookes dark space were observed. Hertz, who experimentally proved the
existence of electromagnetic rays believed that electromagnetic rays are produced from
cathode. Julius Plucker discovered that magnetic field affects the cathode rays. Thomson
showed that the cathode rays in Hertz experiment were affected by electric field. This showed
that the cathode rays cannot be electromagnetic rays.
J. J. Thomson experimentally determined the ratio of charge to mass of an electron and found
it to be 1.8 * 10exp11 C / kg. Earlier, the ratio of charge to mass was determined for different
ions with the experiments of electrolysis. This ratio for hydrogen ion was 9.6 * 10exp7 C / kg.
Hence, Thomson concluded that the mass of electron should be 10 power- 3 to 10 power - 4 times the mass of hydrogen ion. Thomson called these particles ( electrons ) as primordial particles.
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