Hi guys, Not to put too fine a point on it :) You will find that the "converging rays from a projecting lantern" are collimated to some degree, but this is not the point. It is not the nature of the light source (within reason) that accounts for the cone, rather, it is the forward nature of the scattering when light is refracted from particles much smaller than the wavelength of that light.
A laser pointer does indeed produce a cone. It is not easy to distinguish, however, mainly because its base is quite small to begin with. Ivan > -----Original Message----- > From: George [mailto:in...@dragonbyte.net] > Sent: Thursday, 29 August 2002 5:34 p.m. > To: silver-list@eskimo.com > Subject: Re: CS>Newbie/Particle Size > > > On Wed, 28 Aug 2002 23:58:56 -0400, elixsil...@citlink.net wrote: > > >My research shows the Tyndall Effect or Phenemon refers to > the conical shape > >a flashlight beam will take as it passes through a highly > colloidal sol. How > >pray-tell does the thin line of a laser equate to this? > > As I posted on 8/25 to an earlier inquiry (yours?): > > "The reason Tyndall spoke of a 'cone' and modern > experimenters don't is due to the nature of the light source. > Lasers emit a 'beam' of light where the edges are near to > parallel (collimated) which is why you see a relatively > small spot when the laser is directed towards a far wall. > Flashlight emissions (due to the nature of the reflector) > are uncollimated and spread very quickly as demonstrated by > the much larger spot when the flashlight is directed > in the same manner as the laser. > > If you want to see a 'Tydall cone' then use a larger > container and a flashlight with a small reflector, such as the > tiny MagLights..." > > To expand a bit: > > "The Tyndall effect may be explained as follows. If a beam > of converging rays, say, from a projection lantern, is > passed through a liquid containing minute particles in > suspension, each of these particles scatters the light rays > that fall on it, becoming, in a sense, a luminous point. > Thus, the entire path of the rays through the liquid becomes > visible..." > > Source: > Colloids & The Tyndall Effect > from General Chemistry > by N. Glinka, > Peace Publishers, Moscow, circa 1960s > > As should be apparent from the above, the Tyndall effect is > the appearance of the reflections themselves , not the > shape which manifests due to the characteristics of the > light source. Your "research" needs to be expanded a > tad. The internet is crammed with explanations of this > effect. A simple search of google.com on 'Tyndall effect > returned 111,000 references and took a mere .41 seconds! > > Regards, > George Martin > > >Johnny Silverseed > > > > > -- > The silver-list is a moderated forum for discussion of > colloidal silver. > > Instructions for unsubscribing may be found at: http://silverlist.org To post, address your message to: silver-list@eskimo.com Silver-list archive: http://escribe.com/health/thesilverlist/index.html List maintainer: Mike Devour <mdev...@eskimo.com>
