A copper sulfate solution is placed in a container that contains coaxial cylindrical copper electrodes, as indicated in the picture.
Uncharged pollen grains are sprinkled in the area between the electrodes. They are observed to circulate counterclockwise when viewed from above. You hypothesize that they are carried along by the circulation of ions in the solution due to the electric and magnetic forces that act on those ions.
Can you tell if the charge on the circulating ions is positive or negative? Explain.
A solution is provided to explain why the charge of ions can not be determined based on the information given.