# When was the energy of the electron first measured?

Can you give a few details? where/how was it measured, was the value .511MeV found right away, etc..

The value found by this experiment is .537 MeV

I do hope that someone can answer the question from an historical point of view, specifying when this experiment was made first, and if Einstein's conjecture (we all know that his 1905 paper was not even intended as a proof by himself) was verified by any different experiment.

• The energy of an electron can have any value greater than or equal to $mc^2$. Maybe you mean the rest energy? It's not very clear what you mean by this question or what you would consider to be an acceptable answer. – Ben Crowell Dec 28 '18 at 20:28

• @user157860 I was trying to be facetious in reference to $E = mc^2$ . I failed. – Carl Witthoft Sep 20 '18 at 15:32