Question

Explain the discovery of electron by Thomson.

Answer 1

Electron:

The negatively charged particle that revolves in the shells of atom is known as an electron.

Discovery of electron:

1. J.J. Thomson performed an experiment with cathode ray discharge tube which consists of metal electrodes on either ends.
2. Electrode connected to negative terminal of battery is cathode and electrode connected to positive terminal is anode.
3. The tube is connected to a vacuum pump to control the pressure of gas in the tube.
4. Electricity is passed through the tube and radiations were observed to be emitted from cathode to anode.
5. These radiations which are emitted from the negative electrode are known as cathode rays.
6. Fluorescence was emitted when these rays struck the walls of discharge tube.
7. The charge to mass ratio of the cathode rays was found to be same as that for an electron.
8. Thus, cathode rays are said to be a stream of electrons.

Thus, electrons were discovered by J.J. Thomson with the help of cathode ray discharge tube experiment.