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How do they measure the mass of the electron in units of MeV/c*c ? 
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#1
Aug3004, 02:38 AM

P: n/a

What is the experimental system used to determine that an electron has a mass of 0.511 MeV/c*c ?
I'd like to learn about methods other than Millikan's oil drop and Thomson's charge/mass ratios. What is the modern way to generate a value with those units? 


#3
Aug3004, 06:23 AM

P: 29

The units come from the equation E =mc^2
If you rerewite the equation in terms of units eV = kg c^2 and rearrange it for mass, you get kg = eV/c^2 and so the numerical value for the mass of the electron is equal to the numerical value of its energy/c^2. So we can give mass in terms of eV/c^2 


#4
Aug3004, 10:10 AM

P: n/a

How do they measure the mass of the electron in units of MeV/c*c ?
I understand what you are saying, but I believe that there is some sort of experimental equipment setup that can and has been used to physically measure the 0.511 MeV or 0.511 MeV/c2 values. It is that info I am after. I would be grateful for any references or links that reveal the nature of that experimental equipment.
Thanks! 


#5
Aug3004, 11:19 AM

Emeritus
Sci Advisor
PF Gold
P: 4,014

Observations of the energy/wavelength/frequency of the gammas which result from the annihilation of electrons and positrons?



#6
Aug3004, 11:24 AM

Emeritus
Sci Advisor
PF Gold
P: 5,533

There is no experimental method to single out any system of units. It doesn't matter if you report the measured value of the mass in kilograms, slugs, or dynes/g. You can always convert to MeV/c^{2}.



#7
May1111, 01:21 PM

P: 4

Hello! I'm also confused regarding these units, given the equation E=[tex]\gamma[/tex]mc^{2}, i am to show the mass of a proton in the units MeV/C^2, however i have no idea how to convert into these units. Is this form of the display of mass actually a measure of the relativistic energy that the particle has?



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