# How do they measure the mass of the electron in units of MeV/c*c ?

by what_are_electrons
Tags: electron, mass, measure, mev or cc, units
 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?
 PF Patron P: 2,873 You can give some credit to nuclear beta decay.
 P: 29 The units come from the equation E =mc^2 If you re-rewite the equation in terms of units eV = kg c^2 and re-arrange 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
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!
 PF Patron Sci Advisor Emeritus P: 3,940 Observations of the energy/wavelength/frequency of the gammas which result from the annihilation of electrons and positrons?
 PF Patron Sci Advisor Emeritus P: 5,539 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/c2.
 P: 4 Hello! I'm also confused regarding these units, given the equation E=$$\gamma$$mc2, 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?

 Related Discussions Introductory Physics Homework 10 Introductory Physics Homework 5 Advanced Physics Homework 1 Quantum Physics 2 General Discussion 0