Question

how did j.j Thomson discover electron as an essential constituent of all matter​

Answer 1

Explanation:

1996 : the electron is discovered by J.J. Thomson

By applying an electric field between the two plates P1 and P2 cathodic rays were deflected along the path indicated in red. They were also deflected by the magnetic field of a coil (blue line) .

Answer 2

Thomson. In 1897 he reported that "cathode rays" were actually negatively charged particles in motion; he argued that the charged particles weighed much less than the lightest atom and were in fact constituents of atoms [Thomson 1897a, 1897b]. ...

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