Question: From what you know about J.J. Thomson's discovery of the electron:
a. Explain how one can use a combination of electric and magnetic fields to determine the ratio of charge to mass of a particle when you don't know either.
b. Tell what there is about such experiments that leads you to conclude that cathode rays are particles?
c. Describe the ways in which Thomson's experiments suggest that atoms contain electrons, i.e., that electrons are parts of atoms?