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5 definitions found

From: DICT.TW English-Chinese Dictionary 英漢字典

 vacuum tube

From: DICT.TW English-Chinese Medical Dictionary 英漢醫學字典

 vacuum tube 名詞

From: Taiwan MOE computer dictionary

 vacuum tube

From: Webster's Revised Unabridged Dictionary (1913)

 Vac·u·um n.; pl. E. Vacuums L. Vacua
 1. Physics A space entirely devoid of matter (called also, by way of distinction, absolute vacuum); hence, in a more general sense, a space, as the interior of a closed vessel, which has been exhausted to a high or the highest degree by an air pump or other artificial means; as, water boils at a reduced temperature in a vacuum.
 2. The condition of rarefaction, or reduction of pressure below that of the atmosphere, in a vessel, as the condenser of a steam engine, which is nearly exhausted of air or steam, etc.; as, a vacuum of 26 inches of mercury, or 13 pounds per square inch.
 Vacuum brake, a kind of continuous brake operated by exhausting the air from some appliance under each car, and so causing the pressure of the atmosphere to apply the brakes.
 Vacuum pan Technol., a kind of large closed metallic retort used in sugar making for boiling down sirup. It is so connected with an exhausting apparatus that a partial vacuum is formed within. This allows the evaporation and concentration to take place at a lower atmospheric pressure and hence also at a lower temperature, which largely obviates the danger of burning the sugar, and shortens the process.
 Vacuum pump. Same as Pulsometer, 1.
 Vacuum tube Phys., (a) a glass tube provided with platinum electrodes and exhausted, for the passage of the electrical discharge; a Geissler tube. (a) any tube used in electronic devices, containing a vacuum and used to control the flow of electrons in a circuit, as a vacuum diode, triode, tetrode, or pentode.
 Vacuum valve, a safety valve opening inward to admit air to a vessel in which the pressure is less than that of the atmosphere, in order to prevent collapse.
 Torricellian vacuum. See under Torricellian.

From: WordNet (r) 2.0

 vacuum tube
      n : electronic device consisting of a system of electrodes
          arranged in an evacuated glass or metal envelope [syn: tube,
           thermionic vacuum tube, thermionic tube, electron
          tube, thermionic valve]