A doubt on Thomson's Experiments to determine the value of e / m_e

In summary, J.J. Thomson conducted accurate measurements of deflections caused by electric and magnetic fields on electrons to determine the value of e/me, which was found to be 1.75 * 10^11 C kg^-1. This indicates that the ratio of field strengths observed was for a specific electron velocity.
  • #1
Rishabh Narula
61
5
By carrying out accurate measurements
on the amount of deflections observed
by the electrons on the
electric field strength or
magnetic field strength,
Thomson was able to determine
the value of e/me as...
e/me = 1.75 10^11 C kg^-1

would this be a correct understanding of this para-
"This para
is just saying that he made measurements
on how much deflection is being caused by
particular electric and magnetic field strengths
and deduced the ratio from those"
 
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  • #2
Hi,

Why don't you provide a reference when you quote litterally, so that a helper can look at the context ?
Saves everybody time and avoids communication errors !
Even if it says copyright NCERT or something (you link, you don't copy).

The context is more didactical than historic, but I see no discrepancies with your version.
Your 'and deduced the ratio' refers to e/m but can easily be mistaken for |E|/|B| by a reader

But your title mentions doubt. About what, specifically ?
 
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  • #3
Rishabh Narula said:
"This para
is just saying that he made measurements
on how much deflection is being caused by
particular electric and magnetic field strengths
and deduced the ratio from those"
Remember that the observed ratio of field strengths was for a particular electron velocity.
 
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  • #4
BvU said:
Hi,

Why don't you provide a reference when you quote litterally, so that a helper can look at the context ?
Saves everybody time and avoids communication errors !
Even if it says copyright NCERT or something (you link, you don't copy).

The context is more didactical than historic, but I see no discrepancies with your version.
Your 'and deduced the ratio' refers to e/m but can easily be mistaken for |E|/|B| by a reader

But your title mentions doubt. About what, specifically ?
sorry i mean a question
 
  • Like
Likes BvU

1. What is the purpose of Thomson's experiments to determine the value of e/m_e?

The purpose of Thomson's experiments was to determine the ratio of the charge of an electron (e) to its mass (m_e), also known as the specific charge. This was an important step in understanding the structure of atoms and the nature of electricity.

2. How did Thomson conduct his experiments?

Thomson used a cathode ray tube, which is a sealed glass tube with a high voltage source at one end and a fluorescent screen at the other. He applied a magnetic field perpendicular to the path of the cathode rays and measured the amount of deflection. He also varied the electric field to observe the effect on the deflection.

3. What were the results of Thomson's experiments?

Thomson's experiments showed that the deflection of the cathode rays was directly proportional to the applied electric and magnetic fields. This allowed him to calculate the ratio of e/m_e, which he found to be 1.76 x 10^11 Coulombs/gram.

4. How did Thomson's experiments contribute to the development of atomic theory?

Thomson's experiments provided evidence for the existence of subatomic particles, specifically the electron. This challenged the previously accepted theory of the atom as indivisible and led to the development of the plum pudding model of the atom, which was later replaced by the nuclear model by Rutherford.

5. Are Thomson's experiments still relevant today?

Yes, Thomson's experiments are still relevant today as they laid the foundation for further research on subatomic particles and the structure of atoms. The value of e/m_e has been refined over the years and is now known as the electron charge-to-mass ratio, which is an important constant in many areas of physics.

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