MadSci Network: Physics |
Vern: Yes, dust is radioactive, whether or not it is on your TV set or on your kitchen table. Most materials contain some unstable (or, radioactive) atoms. The TV does not make the dust radioactive, but it can cause some of the more radioactive dust particles to attach to the TV screen. This will make a radiation detector respond with more counts per minute when placed near "TV screen dust" than it would when placed near "kitchen table dust." The reason for this phenomenon is that the naturally-occuring radioactive gas, radon, remains radioactive after it decays, and it will decay several more times in the next 30 minutes or so, after the radon decays. It is these subsequent decays (after radon) that you are detecting from your TV screen dust. What happens is this: In all air, every cubic meter contains a certain number of dust particles as well as a number of atoms of radon. Radon is radioactive, but chemically it is a noble gas, so it doesn't bond with other atoms. However, as soon as it decays, it becomes an atom of polonium and, just as important, it usually also has an electric charge since some of its 84 electrons are knocked loose by the alpha particle which just came blasting out of the nucleus of the radon atom. This charged atom of polonium is attracted to any nearby particle of dust and frequently becomes attached to the dust. This dust particle (still with a + charge) is then attracted to the negatively charged surface of a TV screen. But, the uncharged dust particles are not. Therefore, dust (with radioactive polonium attached to it) is preferentially drawn to a charged surface such as a TV screen. That is why "TV screen dust" always seems to be more radioactive than other dust. And, your comment about using a TV screen (or some other charged surface) to help clean up certain nuclear materials is an approach that could be effective in certain situations. I hope this helps. Feel free to email me directly if there is anything I might be able to clarify for you.
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