Key terms electric dipole closed surface electric flux electric charge surface integral electrostatics Gauss's law electron Gaussian surface proton Faraday' s icepail neutron experiment nucleus electric potential energy positive ion electric potential negative ion voltage ionization electron volt conductor equi potential surface insulator gradient point charge cathode-ray tubeelectric charge electrostatics electron proton neutron nucleus positive ion negative ion ionization conductor insulator point charge Key terms: electric dipole closed surface electric flux surface integral Gauss’s Law Gaussian surface Faraday’s icepail experiment electric potential energy electric potential voltage electron volt equipotential surface gradient cathode-ray tube