Q.What is observed when visible light is passed through a hydrophobic colloidal solution?

Colloidal dispersions show several characteristic properties. The Tyndall effect is the scattering of light by colloidal particles, which makes the path of a light beam through the dispersion visible (as a bright 'Tyndall cone') to an observer at right angles, unlike a true solution, through which light passes without a visible path; it requires the particle diameter to be comparable to the light's wavelength and a large difference in refractive index between the phases, and is used to estimate particle size/number and to distinguish colloids from true solutions. Colour depends on the wavelength scattered, the viewing angle (scattered vs transmitted light), and particle size (e.g. fine gold sol is red, coarser gold sol is purple). Brownian …