What observation did J.J Thomson make to suggest that an electron has a negative electric charge?
J.J. Thomson was studying electricity during his time. He did an experiment where he used a cathode and saw cathode rays. Thomas observed that when a small paddle was placed in a wheel in the path of rays, the wheel would turn. This observation suggested that the cathode rays consisted of tiny that were hitting paddles of the wheel. Thus, it suggested that an electron had a negative charge.
