J.J. Thomson's cathode ray experiment

In summary, Rohlf's Modern Physics textbook discusses the value of q/m for the electron, which was found to be substantially smaller than that of ionized atoms through electrolysis. This led to two extreme possibilities: either the electron charge is much smaller than that of an ionized atom, or the electron mass is much smaller. The book's description may be incorrect, as it seems that m/q should be smaller for electrons, not q/m. However, this confusion may arise due to different conventions.
  • #1
jcortez91
7
0
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?


Thanks,
Alex
 
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  • #2
Looks like Rohlf has it backwards - good catch.
The confusion may arise because some refer to m/q and some to q/m.
 
  • #3
Okay thanks. It was bugging me.
 

1. What was J.J. Thomson's cathode ray experiment?

J.J. Thomson's cathode ray experiment was an experiment conducted in the late 19th century to study the nature of cathode rays, which are streams of electrons emitted from the negative electrode (cathode) of a high-voltage electrical discharge tube.

2. What were the key findings of the cathode ray experiment?

Thomson's experiment showed that cathode rays were negatively charged particles that could be deflected by electric and magnetic fields. He also discovered that these particles had a much smaller mass compared to atoms, leading to the development of the "plum pudding" model of the atom.

3. How did Thomson's experiment contribute to the understanding of atomic structure?

Thomson's experiment provided evidence that atoms were not indivisible, as previously thought. It showed that atoms were made up of smaller, negatively charged particles (electrons) and positively charged particles (later identified as protons). This challenged the existing model of the atom and led to further research and developments in atomic theory.

4. What was the significance of the cathode ray experiment in the field of physics?

The cathode ray experiment was significant in that it provided experimental evidence for the existence of subatomic particles and challenged the prevailing view of the atom. It also paved the way for further research and developments in the field of particle physics, leading to the development of modern atomic theory.

5. How is the cathode ray experiment relevant today?

The cathode ray experiment laid the foundation for our understanding of atomic structure, which is still relevant today. It also paved the way for further advancements in particle physics and the development of technologies such as cathode ray tubes, which are used in television and computer screens.

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