Radioactivity and Half-Life

There are three types of nuclear radiation; alpha, beta and gamma. Alpha, a helium nucleus, is the least penetrating and is stopped by a sheet of paper. Beta, a high-energy electron, is stopped by a thin sheet of aluminium, and gamma, a high-energy photon is stopped by a thick sheet of lead.

These radiations are all ionising, which means that they can pull the electrons out of atoms.

Different radioactive materials have different half-lives ranging from seconds to millions of years! The half-life is the time taken for the radioactivity of a sample to drop by half. Radiation can be used to date rocks and bones, treat cancer, kill germs and detect smoke or the thickness of paper.