STRUCTURE OF ATOM Sub-atomic particles Discovery of Electron Electron was discovered by J J Thomson by Cathode ray discharge tube experiment . A cathode ray tube is made of glass containing two thin pieces of metal (electrodes) sealed in it. The electrical discharge through the gases could be observed only at very low pressures and at very high voltages.When a very high voltage (about 10,000 volts) is applied between the two electrodes, no electric discharge occurs at normal pressure. When the pressure of the gas inside the tube is less than 1 mm of mercury, a dark space appears near the cathode. When the pressure is reduced to 0.01 mm Hg, it fills the whole tube. When the pressure is further reduced, the electric discharge passes between the electrodes and the tube begins to glow. This is due to the striking of some invisible rays from the cathode. These rays which start from the cathode and move away from it, in straight lines are call ed cathode Rays or cathode ray part...
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