# Determining the charge or mass of an electron

1. Dec 2, 2003

### katherine

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?

2. Dec 2, 2003

### dlgoff

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

Don

3. Dec 3, 2003

### katherine

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. Dec 3, 2003

### dlgoff

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. Dec 3, 2003

### chroot

Staff Emeritus
Could you build a miniature mass spectrometer?

- Warren

6. Dec 19, 2003

### nautica

So electrons are considered to have mass?????

Nautica

7. Dec 19, 2003

### 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.

8. Dec 23, 2003

### 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.

Thanks
Nautica

9. Dec 23, 2003

### dlgoff

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.