It explains how electrons are accelerated by an electron gun and then deflected by a magnetic field created by Helmholtz coils. The experiment measures the mass of an electron by analyzing the ...

What does increase dramatically is the energy (and the mass). At the beginning of an experiment, a beam of electrons may have a rest energy of 1/2 million electron volts; it is directed through a ...

He called it a neutron, and imagined it as a paired proton and electron ... particle -- one with the same mass as a proton, but with zero charge. His experiments were successful.