Question

Tyndall effect depends upon the:

• A. Both (a) and (c)
• B. Charge on the colloidal particles
• C. Osmotic pressure of colloidal solution
• D. Difference between the refractive indices of dispersed phase and dispersion medium

Answer 1

The correct option is D Difference between the refractive indices of dispersed phase and dispersion medium

Tyndall effect:

• If a strong beam of light is passed through a colloidal sols placed in dark place, path of the beam gets illuminated. This effect is called Tyndall effect.
• This effect was first observed by Faraday later studied in detail by Tyndall.
• This effect arises due to scattering of light by colloidal particles in all directions. Thus, scattering of light illuminates the path of beam in the colloidal dispersion.

Condition for Tyndall effect:

1. The diameter of dispersed particles should not be much smaller than the wavelength of light.
2. The refractive indices of dispersed phase and dispersion medium should differ greatly in the magnitude.

Hence, Tyndall effect depends on the difference between the refractive indices of dispersed phase and dispersion medium.