VACUUM TUBE

an electron tube from which almost all air or gas has been evacuated: formerly used extensively in radio and electronics. —HDA Tapes (Oakland Lectures) Approved Glossary (16.4.92)

a glass tube normally one to six inches long and containing little to no air (a vacuum), formerly used extensively in radios, televisions, computers and other electronic devices to regulate and control electric currents or electronic signals necessary to the operation of such equipment. Because air is resistive to electrical flow, a vacuum is created in the tube so that electricity can flow inside of it.an electron tube from which almost all air or gas has been evacuated formerly used extensively in radio and electronics.a sealed tube from which most of the air has been removed, and into which an electrode from outside projects; used in radio and television sets, radar, electron microscopes and other devices to control flows of electric current.