J.J thomsons Catode ray - Why hydrogen gas?

In summary, J.J. Thomson used hydrogen gas in a chamber to create charged particles which are deflected by magnets to study cathode rays.
  • #1
christian0710
409
9
Hi,

I'm curious about J.J thomsons Catode ray, and i have a few questions:

In J.J. Thomsons Catode ray setup he has hydrogen gas in a chamber through which the catode ray is beamed. What is the role of hydrogen gas? What could he use the hydrogen gas for?


And how could he make up the assumption that The distance the electron is deflected when charging the metal plates in the catode ray tube, is proportional to the charge of the electron and inversly proportional to the mass of the particle?

I'm watching the MIT lecture, and I was just very curious about this :)
https://www.youtube.com/watch?v=l-BNoAPe6qo&list=PLCDDBC844A74EED42&index=2
 
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  • #2
See http://www.nyu.edu/classes/tuckerman/adv.chem/lectures/lecture_3/node1.html

Most any gas will work; the gas is ionized in the first chamber, and generates a beam of charged particles which are deflected by the magnets.

Cathode rays were already known, so his experiment was designed to study them in a particular way.
See https://en.wikipedia.org/wiki/Cathode_ray#History
 
  • #3
christian0710 said:
Hi,

In J.J. Thomsons Catode ray setup he has hydrogen gas in a chamber through which the catode ray is beamed. What is the role of hydrogen gas? What could he use the hydrogen gas for?
Cathode rays were first discovered when trying to conduct electricity through rarified gases.
An occasional positive ion will be attracted to the cathode, and this can knock loose electrons, the electrons can knock loose electrons from the gas, producing positive ions, which get attracted to the cathode again. This happens also in neon and fluorescent lamps.
look up "cold cathode" or "gas discharge lamp"

This method also produces positive hydrogen ions, which thomson was able to detect as well.

The more efficient method of producing cathode rays with a heated cathode in a vacuum wasn't in use yet.

And how could he make up the assumption that The distance the electron is deflected when charging the metal plates in the catode ray tube, is proportional to the charge of the electron and inversly proportional to the mass of the particle?
This is a consequence of threating the electron as a point mass in a constant electric field, and using F = ma.
 
  • #4
willem2 said:
Cathode rays were first discovered when trying to conduct electricity through rarified gases.
An occasional positive ion will be attracted to the cathode, and this can knock loose electrons, the electrons can knock loose electrons from the gas, producing positive ions, which get attracted to the cathode again. This happens also in neon and fluorescent lamps.
look up "cold cathode" or "gas discharge lamp"

This method also produces positive hydrogen ions, which thomson was able to detect as well.

The more efficient method of producing cathode rays with a heated cathode in a vacuum wasn't in use yet.


Thank you so much for that great explanation.


willem2 said:
This is a consequence of threating the electron as a point mass in a constant electric field, and using F = ma.
That sounds really interesting. So does it mean that he rearranged Newtons equation for force to a=F/m and assumed that force must be the charge of the electron? Is there a derivation for it or is this how simple it was?
 
  • #5
&t=0s

Hello,

J.J. Thomson's experiments with cathode rays were groundbreaking in the field of physics and led to important discoveries about the nature of electricity and matter. The role of hydrogen gas in his experiments was to provide a medium for the cathode rays to travel through. Hydrogen gas is a good conductor of electricity and allows for the movement of charged particles, such as electrons, which are the focus of Thomson's experiments.

Thomson used the hydrogen gas to observe the behavior of the cathode rays as they passed through the gas. By charging metal plates in the cathode ray tube, he was able to deflect the cathode rays and measure the distance of deflection. This allowed him to make the assumption that the distance of deflection was proportional to the charge of the electron and inversely proportional to its mass. This was a significant discovery as it provided evidence for the existence of a subatomic particle, the electron, and its properties.

Thomson's experiments with cathode rays paved the way for further research into the structure of atoms and the discovery of other subatomic particles, such as protons and neutrons. His work also laid the foundation for the development of modern particle physics. I hope this helps to answer your questions and provides some insight into the significance of J.J. Thomson's experiments with cathode rays. Thank you for your interest in this fascinating area of science.
 

Related to J.J thomsons Catode ray - Why hydrogen gas?

Frequently Asked Questions about J.J Thomson's Catode Ray - Why Hydrogen Gas?

Q: Who is J.J Thomson and what is the significance of his Catode Ray?

A: J.J Thomson was a British physicist who is credited with the discovery of the electron. His Catode Ray experiment provided evidence for the existence of electrons and paved the way for modern atomic theory.

Q: What is a Catode Ray?

A: A Catode Ray is a beam of electrons emitted from the negative electrode (cathode) in a vacuum tube. It can be observed using a fluorescent screen placed in its path.

Q: How did J.J Thomson use hydrogen gas in his Catode Ray experiment?

A: J.J Thomson used hydrogen gas as the medium through which the Catode Ray traveled in his experiment. He found that when the gas was present, the beam of electrons was deflected in a magnetic field, providing evidence that the particles in the ray had a negative charge.

Q: What was the purpose of using hydrogen gas in the Catode Ray experiment?

A: Hydrogen gas was used as a way to show that the properties of the Catode Ray were not specific to a particular gas, but were instead a property of the electrons themselves. This helped to support Thomson's theory that electrons were fundamental particles.

Q: What impact did the Catode Ray experiment have on our understanding of the atom?

A: The Catode Ray experiment provided evidence for the existence of electrons and helped to support the idea that atoms were composed of smaller, fundamental particles. This experiment was a crucial step in the development of modern atomic theory and our understanding of the structure of atoms.

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