Question

Tyndall effect depends upon the

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

Answer 1

The correct option is C 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.