Vacuumelt - Salvat 2005
Salvat 2005 · 2005
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About this card
A vacuum tube, electron tube, thermionic valve, or tube is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied. It takes the form of an evacuated tubular envelope of glass or sometimes metal containing electrodes connected to external connection pins.
Summary from Wikipedia (CC BY-SA 4.0).