He nuclei
Alpha?rays are actually high speed?particles. Early researchers tended to refer to any form of energetic?radiation?as?rays, and the term is still used. An?alpha particleis made up of two protons and two neutrons, all held together by the same strong nuclear force that binds the nucleus of any atom.
electrons and electromagnetic radiation of wavelengths shorter than X-rays
??-rays and???-rays are respectively electrons and electromagnetic radiation of wavelengths shorter than X-rays
N(t)=N(0)e?\lambda t
Radioactivity:?Law of Radioactive Decay.?Radioactivity?is the phenomenon exhibited by the nuclei of an atom as a result of?nuclear?instability. It is a process by which the nucleus of an unstable atom loses energy by emitting?radiation.Radioactivity?was discovered by Henry Becquerel completely by accident.
the time in which N has been reduced to one-half of its initial value
The half-life?T1/2of a radionuclide is the time in which N has been reduced to one-half of its initial value
the time at which N has been reduced to?e?1of its initial value
The mean life t of a radionuclide is the time at which N has been reduced to?e?1of its initial value