Hi Marshall, Please review the following article. It will explain why 650nm coherent laser radiation collimated to a beam width of one mm will scatter isotropic in the presence of large numbers of small particles, http://www.erpt.org/032Q/Wedd-01.pdf
Here is another explaining how this effect is utilized in making particle size analyzers work. http://www.microtrac.com/laserdiffraction.cfm Best Regards, Arnold Beland www.atlasnova.com ----- Original Message ----- From: "Marshall Dudley" <mdud...@king-cart.com> To: "Arnold Beland" <abela...@comcast.net> Sent: Thursday, May 01, 2008 12:48 PM Subject: Re: CS>"Tyndall Effect" with no silver particles at all > Arnold Beland wrote: >> It is possible to observe the "Tyndall Effect" with no silver >> particles at all. Here is a good explanation of this.: >> http://math.ucr.edu/home/baez/physic.../blue_sky.html >> <http://math.ucr.edu/home/baez/physics/General/BlueSky/blue_sky.html> >> A decent red laser pointer at exactly 650nm and constant power output >> regardless of battery condition is far more reliable. They are >> available on ebay for as little as $9.00. Stay away from any made in >> China. >> Best Regards, >> Arnold Beland >> www.atlasnova.com <http://www.atlasnova.com> > True for blue, which is why the sky is blue, but not for red, which is > too long a wavelength for significant scattering with small to medium > sized molecules. Tyndall effect has nothing to do with silver, it has > to do with scattering by particles approximately the size of the > wavelength of light being scattered and larger. > > Marshall >
