DISCOVERY OF THE ELECTRON - CATHODE RAYS AND PROPERTIES OF CATHODE RAYS

DISCOVERY OF THE ELECTRON - CATHODE RAYS



The electron was discovered as a result of the study of conduction of electricity through gases at low pressures. The experiments were conducted in discharge tubes. When a high potential is applied to a gas taken in a discharge tube at very low pressure, certain rays are emitted from the cathode. These rays are called CATHODE RAYS


PROPERTIES OF CATHODE RAYS


From the various experiments carried out by J.J Thomson  and others, the cathode rays have been found to possess the following properties.

1. They start from cathode and move towards the anode in straight lines.
2. Cathode rays consist of material particles.
3. When an electric field is applied to a stream of cathode rays, they get deflected  towards the positive plate of the electric field. This shows that the particles in the cathode rays carry negative charge.
4. Cathode rays are deflected by magnetic fields in a direction expected for negative particles.
5. Cathode rays produce X-rays when they strike against the surface of hard metals like tungsten, copper etc.
6. Materials coated with fluorescent or phosphorescent substances produce glow when hit by cathode rays.

                       All these observations led to the conclusion that cathode rays consist of fast moving negatively charged particles. These particles were named ELECTRONS.