electrons travel through the partial vacuum inside the tube, flowing from the filament to the positively charged plate.
electrons and positrons have opposite electric charges, so they happily and fatally attract each other.
The electromagnetic force between the electrons lets you pick up the cup, counteracting gravity in the process.
electron e·lec·tron (ĭ-lěk'trŏn')
A stable subatomic particle in the lepton family having a rest mass of 9.1066 × 10-28 gram and a unit negative electric charge of approximately 1.602 × 10-19 coulomb. Also called negatron.
An elementary particle with a negative charge and a very small mass. Electrons are normally found in orbits around the nucleus of an atom. The chemical reactions that an atom undergoes depend primarily on the electrons in the outermost orbits (the valence electrons).
Note: The movement of large numbers of electrons through conductors constitutes an electric current.