Determining the charge or mass of an electron

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Discussion Overview

The discussion revolves around designing an experiment to determine either the charge or mass of a single electron, inspired by Millikan's oil drop experiment. Participants explore various experimental approaches and clarify concepts related to the mass and charge of electrons.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests using Thomson's apparatus to find the e/m ratio, inquiring about the availability of a CRT.
  • Another participant proposes a variation of Coulomb's experiment, involving suspended masses and induced charges, and questions the need for pendulum properties in the calculations.
  • A suggestion is made to build a miniature mass spectrometer as an alternative experimental design.
  • There is a question raised about whether electrons are considered to have mass, which prompts clarification about the measured mass of electrons.
  • A participant expresses confusion regarding the nature of electrons, associating them with wave behavior and questioning their mass, leading to a distinction between electrons and massless photons.

Areas of Agreement / Disagreement

Participants express differing views on the nature of electrons, particularly regarding their mass and wave-particle duality. There is no consensus on the experimental designs proposed, as multiple approaches are discussed without agreement on a single method.

Contextual Notes

Some participants reference established measurements of electron mass, while others express confusion about the implications of wave behavior in relation to mass. The discussion includes assumptions about the experimental setup and the definitions of mass and charge.

Who May Find This Useful

This discussion may be of interest to students and educators in physics, particularly those exploring experimental design and the fundamental properties of electrons.

katherine
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I have to design an experiment that determines either the charge or mass of a single electron, something like was millikan did, for under $500 give or take a bit. We have some equipment, but not much, already. The design has to be innovative and doesn't have to be, or shouldn't be, exactly like millikan's experiment. Any ideas?
 
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I have to design an experiment that determines either the charge or mass of a single electron, something like was millikan did, for under $500 give or take a bit. We have some equipment, but not much, already. The design has to be innovative and doesn't have to be, or shouldn't be, exactly like millikan's experiment. Any ideas?

It occurred to me that you can find the e/m ratio using Thomson's apparatus. Do you have a CRT you could use?

Don
 
I was thinking that I could use something like coloumb's experiment. I was thinking that I would suspend two masses from a rod then induce a like charge in each. Then somehow from their deflection could I calculate the charge? Would I have to use pendulum properties to carry through with this?
 
I was thinking that I could use something like coloumb's experiment. I was thinking that I would suspend two masses from a rod then induce a like charge in each. Then somehow from their deflection could I calculate the charge? Would I have to use pendulum properties to carry through with this?



Yes and yes. When the displacement is in equilibrium, the electrical force equals the gravational force . Use columb's law and Newton's law.
 
Could you build a miniature mass spectrometer?

- Warren
 
So electrons are considered to have mass?

Nautica
 
originally posted by nautica
So electrons are considered to have mass?
That seems a strange question! Yes, of course, electrons are not only "considered" to have mass, they have mass that has been accurately measured at about 9.1x 10-31kg.
 
Originally posted by HallsofIvy
That seems a strange question! Yes, of course, electrons are not only "considered" to have mass, they have mass that has been accurately measured at about 9.1x 10-31kg.

I guess I am confused. I was under the assumption that electrons act as waves and were actually a point of zero mass? Enlighten me, please.

Thanks
Nautica
 
I guess I am confused. I was under the assumption that electrons act as waves and were actually a point of zero mass? Enlighten me, please.

You might be thinking of photons. They are point particles with no mass. They are the carrier of the electromagnetic force determined by electrons, which are also point particles but have mass.
 

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