MadSci Network: Physics
Query:

Re: Why does my TV collect radioactive dust?

Date: Tue Nov 30 14:10:02 2004
Posted By: Gerald Gels, Certified Health Physicist
Area of science: Physics
ID: 1101095325.Ph
Message:

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.


Current Queue | Current Queue for Physics | Physics archives

Try the links in the MadSci Library for more information on Physics.



MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci


MadSci Network, webadmin@madsci.org
© 1995-2003. All rights reserved.