Who discovered electron?

J.J. Thomson

The correct answer is option 1. J.J. Thomson.

J.J. Thomson discovered the electron through his experiments with cathode rays in the late 19th century. Cathode rays were observed in vacuum tubes, which were sealed glass tubes containing metal electrodes and evacuated of air. Thomson conducted experiments to study the properties of these cathode rays and their behavior in electric and magnetic fields.

One of Thomson's key experiments involved the use of a cathode ray tube with electric and magnetic fields applied to it. He found that cathode rays were deflected by electric fields in a manner consistent with negatively charged particles. Additionally, when a magnetic field was applied perpendicular to the electric field, the cathode rays were deflected in a circular path, indicating that they were charged particles.

Based on these and other experiments, Thomson proposed that cathode rays were streams of negatively charged particles, which he named "electrons." This discovery fundamentally changed the understanding of atomic structure, providing evidence for the existence of subatomic particles and leading to the development of the plum pudding model of the atom.