Subject: Physics
The phenomenon of spontaneous emission of highly penetrating radiations from heavy elements occurring in nature is called natural radioactivity. The phenomenon in which radioactivity can be induced by artificial means through nuclear transmutation is known as artificial radioactive radiations. They are named as α, β, and γ radiations.
After the discovery of natural radioactivity, a large number of experiments were conducted to determine the nature of radiations emitted by the radioactive substances.
A small hole is drilled in a lead block in which a piece of the radioactive sample such as radium is placed and a narrow beam of radiation emerges out of the hole. The nature of the radiation is studied by applying an electric field or magnetic field as in the figure. In both cases, the narrow beam splits into following three components.
Three types of emission from a radioactive nuclide are observed as discussed above. In addition to these, electron capture and positron emission is also considered as radioactive decay. Hence there are five kinds of radioactive decay. Examples of this decay are given below: 3C12
Following are the properties of radioactive radiations.
Properties of α-particles
Properties of β-particles
Properties of γ-particles
There are two types of forces are acting there. One of force is attractive and other is repulsive. If attractive force dominates the repulsive force, the nucleus becomes stable but if repulsive force is too much greater than the attractive force, the nucleus becomes unstable. Such unstable nucleus emits radioactive radiations. Hence, the unstable nucleus is the main cause of radioactivity.
Reference
Manu Kumar Khatry, Manoj Kumar Thapa, et al. Principle of Physics. Kathmandu: Ayam publication PVT LTD, 2010.
S.K. Gautam, J.M. Pradhan. A text Book of Physics. Kathmandu: Surya Publication, 2003.
The phenomenon of spontaneous emission of highly penetrating radiations from heavy elements occurring in nature is called natural radioactivity.
The phenomenon in which radioactivity can be induced by artificial means through nuclear transmutation is known as artificial radioactive radiations. They are named as α, β and γ radiations.
After the discovery of natural radioactivity, a large number of experiments were conducted to determine the nature of radiations emitted by the radioactive substances.
The unstable nucleus is the main cause of radioactivity.
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