Distance square law
The distance square law is a term used in radiation protection . It states that due to the divergence of the radiation, the dose rate per area decreases with increasing distance from the radiation source, inversely proportional to the square of the distance. If the distance z. B. doubled, the dose rate per area is reduced to a quarter, if the distance is tripled to a ninth, etc.
The law applies strictly only to point sources; it always applies approximately when the extent of the source is small compared to the distance. The law is not only important for radiation protection in practice, but also, for example, in the health sector ( radiation therapy ).
In the very rare case of a linearly extended radiation source, the dose rate per area only decreases in inverse proportion to the distance. In the case of a homogeneously radiating surface that is larger than the distance (also rare), the dose rate per surface is the same at every distance.
The law of the square of the distance applies to all energy quantities . The field sizes are to be distinguished from energy sizes .
See also: