What happens when light passes through colloid?

Tindal effect, also known as Tindal phenomenon, or Tindal phenomenon, Dinsel effect and Tindal effect.

When a beam of light passes through the colloid, a bright "path" can be observed in the colloid from the direction perpendicular to the incident light, and the appearance of Tindal effect also means that light can be seen.

Photography circle, also known as "Jesus light", usually appears in the early morning, sunset or when there are more clouds after the rain. There is fog or dust in the atmosphere, just as the sun shines on it, divided into strips, sometimes a large piece, which is particularly spectacular.

cause

In the process of light propagation, when light shines on particles, if the particles are many times larger than the wavelength of incident light, light reflection will occur; If the particles are smaller than the wavelength of the incident light, light scattering will occur. What is observed at this time is the light radiated by light waves around the particles, which is called scattered light or milky light. Tindal effect is a phenomenon of light scattering or milky light.

Because the diameter of true solution particles is generally less than 1nm, colloidal particles are between solute particles and suspension particles in the solution, and their diameter ranges from 1 ~ 100nm. It is less than the wavelength of visible light (400 nm ~ 700 nm), so when visible light passes through colloid, it will have obvious scattering effect.

For real solution, although the molecules or ions are small, the intensity of scattered light decreases obviously with the decrease of the volume of scattered particles, so the scattering effect of real solution on light is very weak. In addition, the intensity of scattered light also increases with the increase of particle concentration in the dispersion system.