Why do particles in a colloid refract light?

while particles in a solution do not?

A true solution is one in which the solute is completely dissolved, in particles so small that they do not refract a beam of light passed through them.

Because truly dissolved solute particles are on the order of 1 nm or less in diameter, they are too small to reflect or refract light. Therefore, except for metal alloys, true solutions are transparent. (Transparent and colorless do NOT mean the same thing.)



A colloid is a mixture in which the solute particles remain in suspension, but are large enough to refract light.

:eyes:

:)

I posted a photo for you, did you get this one?


(Sorry to threadjack, OP).

:)

we have a winner!

SATAN? Or perhaps...

Any true colloid of silver, or any other metal, will produce a Tyndall Cone once a narrow beam of light pierces the medium. A laser pointer works best. As the light passes through the colloid, each particle of silver refracts the light across other silver particles. The colloid becomes a sea of submicroscopic mirror balls, creating a glowing tunnel of light much wider than the original beam. Therefore, even clear colloidal silver can be given a visual test that will prove the incredibly tiny particles are there. Because clear colloids contain the smallest silver particles, the Tyndall cone will be faint, but still visible to the unaided eye.

The Tyndall effect is usually applied to the effect of light scattering on particles in colloid systems, such as suspensions or emulsions. It is named after the Irish scientist John Tyndall. The Tyndall effect is used to differentiate between the different types of mixtures namely solution, colloid and suspension. For example, the Tyndall effect is noticeable when car headlamps are used in fog. The light with shorter wavelengths scatter better, thus the color of scattered light has a bluish tint. This is also the reason as to why the sky looks blue - the light from the sun is scattered and we see the blue light because it scatters better.

This effect occurs because short wavelengths of light towards the blue end of the spectrum hit the coloidal particles in the earths atmosphere and are reflected down to the earths surface. Longer wavelengths towards the red end of the spectrum are not affected by the particles and pass on through the earths atmoshpere. This causes blue light to be reflected down to the earths surface which makes the sky appear blue.

I saw this once many years ago on the Mr Wizard show...that man was a GENIUS! ;)

particles in a solution aren't particles in suspension (unlike a colloid) thay have dissolved and intermingled at a molecular level with the solvent.

Funnily enough, solutes (the stuff that dissolves) can alter the refractive index of the solution.

natural photonic interaction with translucent subsurface scattering along the scale of non-fresnel refractivitey!

14% of all people know THAT...

Now let us NEVER speak of this again.

:shrug:

:kick: