what did j.j. thomson discover the electron
Jul 24, 2014. J.J. Thomson used a cathode ray tube to discover the electron. Cathode ray tubes are vacuum tubes that contain two electrodes - one on each side. One of the electrodes (the cathode) fires electrons at the other (the anode) when voltage is added to the system. When Thomson fired up the tube, he saw a beam of light between the two electrodes. To figure out what they were, he applied a magnetic field and found out that the beam moved toward a positive charge and away from a negative charge.