Question

The Tyndall effect is observed only when following conditions are satisfied

I. The diameter of the dispersed particles is much smaller than the wavelength of the light used.

II. The diameter of the dispersed particle is not much smaller than the wavelength of the light used.

III. The refractive indices of the dispersed phase and dispersion medium are almost similar in magnitude.

IV. The refractive indices of the dispersed phase and dispersion medium differ greatly in magnitude.

(a) I and IV (b) II and IV (c) I and III (d) II and III

Answer 1

Correct option (b) II and IV

Explanation:

Colloidal solutions show Tyndall effect due to scattering of light by colloidal particles in all directions in space. lt is observed only under the following conditions.

(i) The diameter of the colloids should not be much smaller than the wavelength of light used.

(ii) The refractive indices of the dispersed phase and dispersion medium should differ greatly in magnitude.