ABSTRACT
The term radiation covers a variety of very important phenomena in the environment. An important point is that all radiation involves the exchange of energy. Nuclear radiation involves the transmission of particles from a radioactive source. This type of radiation is familiar because of its associations with atomic weapons, nuclear power, and the harmful effects of exposure to radioactivity. The expression electromagnetic radiation may be less familiar but the names of the phenomena to which it applies, for example X-rays, light, infra-red (IR) and ultraviolet (UV) radiation, and radio waves, are in common use. The energy associated with electromagnetic radiation is termed radiant energy. In this form energy can exist in the absence of matter. Above, we might have implied that there is a clear distinction between nuclear and electromagnetic radiation but this is not the case. For example, gamma rays are a type of electromagnetic radiation, but they are also associated with radioactivity (see 24), being emitted by the nuclei of radioactive atoms under certain conditions; they are highly energetic and have considerable penetrating power.
