ELECTRON TUBE.--A vacuum tube or a gas-content tube used for any purpose in wireless work. See Vacuum Tube.
ELECTROSE INSULATORS.--Insulators made of a composition material the trade name of which is Electrose.
ENERGY, ELECTRIC.--See Electric Energy.
ENERGY UNIT.--The joule, which see, Page 308 [Appendix: Definitions of Electric and Magnetic Units].
FADING.--The sudden variation in strength of signals received from a transmitting station when all the adjustments of both sending and receiving apparatus remain the same. Also called swinging.
FARAD.--The capacitance of a condenser in which a potential difference of 1 volt causes it to have a charge of 1 coulomb of electricity.
FEED-BACK ACTION.--Feeding back the oscillating currents in a vacuum tube to amplify its power. Also called regenerative action.
FERROMAGNETIC CONTROL.--See Magnetic Amplifier.
FILAMENT.--The wire in a vacuum tube that is heated to incandescence and which throws off electrons.
FILAMENT RHEOSTAT.--See Rheostat, Filament.