Definition of backpack. 1a : a load carried on the backb : a camping pack (as of canvas or nylon) supported by a usually aluminum frame and carried on the backc : knapsack.
Three types of radioation-Alpha, Beta, Gamma. There are three primary types of radiation: 1  Alpha-these are fast moving helium atoms. 2  They have high energy, typically in the MeV range, but due to their large mass, they are stopped by just a few inches of air, or a piece of paper.3  Beta-these are fast moving electrons. Alpha-these are fast moving helium atoms. 2  They have high energy, typically in the MeV range, but due to their large mass, they are stopped by just a few inches of air, or a piece of paper. 3  Beta-these are fast moving electrons. 4  They typically have energies in the range of a few hundred keV to several MeV.
Most general definition is that radiation is energy that comes from a source and travels through some material or through space. Light, heat and sound are types of radiation. This is very general definition, the kind of radiation discussed in this article is called ionizing radiation. Most people connect the term radiation only with ionizing radiation, but it is not correct. Radiation is all around us.