Discovery of Electron:
In 1897, J. J. Thompson produced experimental evidence for the existence of sub-particles known as electrons in the atom of every element (using the Cathode Ray Experiment).
He showed that when a high electrical potential was applied at very low pressure (about 0.001 mm Hg) on a glass tube using a cathode ray tube, the rays were observed to be emitted from the negative electrodeElectrodes are conductors, in the form of wires, rods or plates, through which current enters and leaves the electrolyte. When the current leaves the electrodes it is known as the cathode... More (cathode) to the positive electrode (anodeAn anode is an electrode of a polarized electrical device through which conventional current enters the device. It is the positive part of electrolytes where oxidation takes place. More).
The rays were also found to be deflected by magnetic and electric fields. Since they emanated from the cathode to the anode, they were called cathode rays. It was then concluded that they must be of opposite charge for them to deflect towards the positive electrode, hence, they must be negatively charged particle electrons.
Cathode Rays:
Cathode rays are streams of negatively charged particles moving in straight lines with high velocities from the Cathode to the Anode.
Properties of Cathode Rays:
1. The rays are emitted at right angles to the electrodes.
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