The cathode is a electrode seat of a reduction, which one then describes as cathodic reduction. It corresponds on the positive terminal (+) in a Battery which outputs and on the negative terminal of the external generator in the case of a electrolyser (electrolysis can be seen like the reaction reverses that which occurs naturally in a pile, from where the inversion of the polarities).
The industrial applications are numerous: for example, the electrolytic Réduction of aluminum is at the base of the production of aluminum; cathode is an element essential of the tank of electrolysis.
Electron tubes
In a electron Tube (tube) the electron S circulate of cathode towards the anode. They are emitted by cathode thanks to the thermionic effect. This one consists of a small tube of Nickel covered with oxide of Baryum and Strontium, materials which support the emission of electrons at temperatures lower than 1000°C. Cathode is heated by the filament in Tungstène isolated by a refractory brick lining slipped inside the small tube. It is said that cathode is with indirect heating . Formerly the tubes were with direct heating, i.e. cathode and the filament did only one. The filament was in thorié Tungstène and was to be heated at temperatures close to 1500°C.The cathode rays are a flow of electrons emitted by a cathode placed in a tube containing a gas with very low pressure and accelerated by an electric field. It is the study of the cathode rays in the Années 1890 which allowed the discovery of the electron.
The Cathode tube or “cathode-ray tube” is an electron tube crossed by an electron beam emitted by a cathode indirectly heated and coming to strike an electroluminescent screen.
Almost the totality of the television sets and most of the screens of computers is equipped with cathode tubes.
Semiconductor S
For a Diode with junction PN, cathode to the doped area NR corresponds.
See too
Carbon Savoy
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