Department of Biological and Physical Sciences, CSMET

The penetration power of the three basic radiations are different. Alpha particles, heavy and possessing 2+ charges on each helium nucleus, can be blocked by a sheet of paper. A beta particle is much light-weight than an alpha particle. It can  penetrate a sheet of paper, but will be blocked by a wood board. Gamma radiation is most penetrative among these radiations. This is because gamma rays are composed of neutral photons with zero rest masses.