Sir Joseph John Thomson

Thomson's study of cathode rays led him to prove the existence of electrons. Thomson knew that cathode rays could be "bent" by the influence of certain magnetic fields. In his experiments, he determined that cathode rays were comprised of particles. He thought that there must be a mathematical ratio of the charge carried by the particles, later known to be electrons, to their mass. As a result of Thomson's work, this tiny particle, the electron, smaller than a hydrogen atom, was identified.