Question

Explain about thermionic emission and radioactivity.

Answer 1

Thermionic emission:

In thermionic emission, a piece of metal having low threshold energy is heated to a high temperature which causes a large amount of vibration in electrons causing it to eventually leave the metal surface. These electrons are then accelerated by a potential difference to create a stream of beta rays.

The rate of emission of electrons depends on:-

1. The material used for the filament.

2. The temperature of the filament.

3. The surface area of the filament.

Radio-activity:

The emission of ionizing radiation or particles caused by the spontaneous disintegration of atomic nuclei is called radioactivity.

Radioactivity refers to the particles which are emitted from nuclei as a result of nuclear instability. Because the nucleus experiences the intense conflict between the two strongest forces in nature, it should not be surprising that there are many nuclear isotopes which are unstable and emit some kind of radiation.