In 1897, a British physicists performed a very important experiment with the cathode ray tube. Near the end of the tube, he placed an electrical field with one electrode containing a positive charge and the other containing a negative charge, as shown in the diagram below.
If you recall from the previous diagram, the cathode rays went straight through the evacuated glass chamber in the absence of an applied electrical field. Now, when the electrical field is applied to the cathode ray, it causes the ray to be deflected toward the positive plate. This indicates that the cathode ray is attracted to the positively charge electrode; therefore, the cathode ray must be composed of negatively charged particles. J.J. Thomson called these negatively charged particles corpsules; however, the scientific community was not thrilled with such a name, so they began calling the negatively charged particles electrons.
