Three radiations
This diagram, copied from an original by Marie Curie, shows the effect a magnetic field can have on different types of radiation. Magnetic fields curve the trajectory of particles carrying an electric charge. Alpha rays, curving to the right, are positively charged, the beta rays curving to the left are negatively charged, and the unaffected gamma rays are electrically neutral. Years later, after 1932, beta particles were observed being curved to the right – this would herald the discovery of the positron, and beta-positive radiation.