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What radiation is, what radioactivity is.
Clearly I have not made the proper distinction between [[radiation]] and [[radioactivity]]. Is one a subset of the other? If not, how are they related? --[[User:Ed Poor|Ed Poor]] <sup>[[User talk:Ed Poor|Talk]]</sup> 18:27, 8 July 2008 (EDT)
Clearly I have not made the proper distinction between [[radiation]] and [[radioactivity]]. Is one a subset of the other? If not, how are they related? --[[User:Ed Poor|Ed Poor]] <sup>[[User talk:Ed Poor|Talk]]</sup> 18:27, 8 July 2008 (EDT)
: Radiation is the product of any body that changes from a higher energy state to a lower energy state. For example, when you run a current through a piece of metal it causes the electrons to move to a higher energy state. As they return to a lower energy state, they emit a photon. This is radiation and how a light bulb works. Čerenkov radiation is produced when a charged body slows down to the speed of light in a different medium. In the case of Čerenkov radiation, a proton is slowed down to 0.75 C (the speed of light in water) and gives off photons. A slower proton is at a lower energy state than a fast one. This concept of energy state also applies to the nucleus of an atom.
: Radiation can be divided into two types - ionizing and non-ionizing. The distinction is how they interact with matter. Non-ionizing radiation are things like microwaves, radio waves, viable light. Ionizing radiation are subatomic particles and high energy photons. This type of radiation can knock off an electron from an atom or molecule leaving an ion. Xrays and even ultraviolet can be ionizing, but they are not produced by a radioactive substance.
: A substance that is radioactive (a radionuclide) emits ionizing radiation naturally. Uranium, radium, radon, carbon-14, etc... For fun, carbon-11, nitrogen-13, oxygen-15 , and fluorine-18 are the radionuclides used in PET scans - radioactive substances are sometimes more familiar elements than the classic big heavy atoms. The distinction is that a substance used to produce x-rays in an x-ray tube is not naturally producing it. Not all ionizing radiation is from a radioactive substance. Gama rays, for example can be formed with supernova. Xrays are given off in the jets from a black hole as electrons are wiped around magnetic fields. --[[User:Rutm|Rutm]] 18:50, 8 July 2008 (EDT)