Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

J.J Thompson's Cathode Ray Experiment

  1. Jun 18, 2011 #1
    When Thompson conducted his cathode ray experiment, how did he know that the negatively charged electrons were so small? He knew that they were deflected in measurable ways by electric and magnetic fields, so he concluded that they must have a very small mass to charge (m/e) ratio. But that could also have been explained by the largeness of charge?
  2. jcsd
  3. Jun 18, 2011 #2
    See Millikan's oil drop experiment. It was only after that experiment that the exact charge and size of the electron was found out.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook