J.J. Thomson discovered the electron in 1897, while working with cathode ray tubes. We can scavenge a tube from an old cathode ray oscilloscope. Apply a voltage to the vertical plates and then subject the tube to a transverse magnetic field, centering the beam spot. This is a replay of Thomson’s experiment. One could also see circular trajectories in the presence of magnetic fields alone, the curvatures changing direction by reversing the direction of the field.
