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J.J. Thomson's cathode ray experiment

  1. May 6, 2012 #1
    In Rohlf's Modern Physics textbook it reads: "The value of q/m for the electron determined by Thomson wan substantially smaller than the values of q/m determined by electrolysis, that is, q/m for the electron is much smaller than for ionized atoms. There were two extreme possibilities: (1) The electron charge is much smaller than the charge of an ionized atom, or (2) the electron mass is much smaller than the mass of an ionized atom (or both!) " (Rohlf 12).

    Of course we know the mass to be much smaller but is the book description correct? It seems to me that m/q should be smaller for electrons, not q/m, because either the mass is smaller or the charge is larger. Could someone shed light on this?

  2. jcsd
  3. May 6, 2012 #2


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    Looks like Rohlf has it backwards - good catch.
    The confusion may arise because some refer to m/q and some to q/m.
  4. May 6, 2012 #3
    Okay thanks. It was bugging me.
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