ABSTRACT
Radioactivity is the emission of radiant energy. It is also the property of certain elements of spontaneously emitting radiant energy, by the disintegration or change of the nuclei of their atoms. This radiant energy may be either electromagnetic wave radiation or it may be particles. The inverse square law states that the radiation intensity per unit area varies inversely with the square of the distance from the source of radiation. The scattering of photons and radioactive particles is the result of interaction between the atoms of the material being transversed and the incident particle, resulting in a change of velocity of and a transfer of energy between the two interacting entities. Beta particles are negative electrons. When they have been ejected from an atomic orbit by interaction with a photon, they are called photoelectrons.
