Question

What are the observations made by Thomson?

Answer 1

Thomson performed an experiment with cathode ray discharge tube which lead to discovery of electron.

Experiment done by Thomson:

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.

Observations made by Thomson:

1. When a source of electricity was connected to the electrodes, there was no flow of electricity between them.
2. When air was removed partially from the tube, electricity started flowing from one electrode to another through the remaining air and gave off a yellowish red light.
3. When pressure was decreased slowly, radiations were emitted from cathode to anode in straight line.
4. When these cathode rays struck the walls of tube, fluorescence was emitted.
5. On further reduction in pressure, the radiations were not emitted.