Determining the charge or mass of an electron

In summary, the conversation was about designing an experiment to determine the charge or mass of a single electron for under $500. Ideas were suggested, such as using Thomson's apparatus or Coulomb's experiment, and the concept of electrons having mass was discussed. It was clarified that electrons have been accurately measured to have a mass of 9.1x10-31kg, while photons are point particles with no mass.
  • #1
katherine
2
0
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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  • #2
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
 
  • #3
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?
 
  • #4
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.
 
  • #5
Could you build a miniature mass spectrometer?

- Warren
 
  • #6
So electrons are considered to have mass?

Nautica
 
  • #7
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.
 
  • #8
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
 
  • #9
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.
 

1. How was the charge of an electron first determined?

The charge of an electron was first determined by physicist Robert A. Millikan in 1909 through his famous oil drop experiment. This experiment involved balancing the downward force of gravity with the upward force of electric field on tiny oil droplets to calculate the charge of an electron.

2. What is the current accepted value for the charge of an electron?

The current accepted value for the charge of an electron is 1.602 x 10^-19 coulombs. This value was determined through various experiments and is considered a fundamental constant in physics.

3. How is the mass of an electron calculated?

The mass of an electron can be calculated using the charge-to-mass ratio (e/m) and the charge of an electron. By measuring the amount of deflection an electron experiences in a magnetic field and knowing the strength of the field, the e/m ratio can be calculated and the mass of an electron can be determined.

4. How does the charge of an electron affect its behavior in an electric field?

The charge of an electron is what causes it to experience a force in an electric field. Since the charge of an electron is negative, it will experience a force in the opposite direction of the electric field. This is why electrons move towards the positive terminal in an electric circuit.

5. Can the charge or mass of an electron change?

The charge and mass of an electron are considered to be constant values and have not been observed to change. However, some theories suggest that in certain extreme conditions, such as near a black hole, the properties of an electron may be altered. But this has not been confirmed by experiments.

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