Answer: In this experiment, he showed/proved that all atoms contain negatively charged electrons, which are smaller than protons and neutrons(protons: positively charged; neutrons: Neither positive nor negative charge), and live on the outside of the Nucleus in a cell. Electrons always have a negative charge, and are also classified as subatomic particles. This helped with multiple experiments of JJ Thomson's. He discovered the electron by experimenting with Crooks, or cathode ray, tube.
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