How were cathode rays produced using a discharge tube?
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"Cathode rays" are simply beams of electrons. The name exists because cathode ray devices predate the discovery of the electron. The sharp shadows produced by Crookes tubes meant that something was travelling in a straight line from the cathode down the tube, so they were named cathode rays.
The vacuum doesn't have much to do with the production of electrons, per se, but without high vacuum, the electrons collide with gas particles before they travel very far. If there's enough gas, you get a plasma rather than a beam of electrons. The electron beam is produced by thermionic emission in hot cathodes—electrons are liberated from a hot filament when the thermal energy is enough for electrons to exceed the filament's work function. In cold cathodes, electrons are released by field emission, where a large applied electric field allows electrons to tunnel away from a metal electrode.
The glow of the glass envelope is luminescence—either fluorescence or phosphorescence (or both). Basically, the electrons striking the glass excite components of the glass to an elevated electronic state which releases light upon returning to the ground state. Normal glass isn't particularly luminescent so tubes designed to produce light (like a CRT) are coated with phosphors.
when gas taken in the tube was subjected to very low pressure maintained by a vacuum pump and high voltage ( 10000) volts, when current flows through the stream of particles moving in the tube from cathode to anode.
therefore the streams of particles were known as cathode rays. the negatively charged electrode ejected electrons from it, which travel towards the positively charged anode.
this confirmed that cathode rays were the electrons.
this experiment was carried out by JJ Thomson .
Hope this helps!