Question

Which condition is required to show the Tyndall Effect by the colloidal solution?

• A. The refractive indices of the dispersed phase and the dispersion medium differ greatly in magnitude.
• B. The refractive indices of the dispersed phase and the dispersion medium are exactly the same in magnitude
• C. The refractive indices of the dispersed phase and the dispersion medium do not differ much in magnitude
• D. None of these

Answer 1

The correct option is A

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

Explanation for the correct options:

Option (A).

Tyndall Effect:

Tyndal effect is seen when light is scattered by colloidal particles,

It depends on:

• Dispersed phase
• Dispersed medium
• Size of the particles.

The figure depicts the situation clearly:

For the Tyndall effect, the following conditions should be satisfied :

• Refractive indices of the dispersed phase and the dispersion medium differ greatly. in magnitude and
• The diameter of the dispersed particles is not much smaller than the wavelength of the light used

Explanation for the incorrect options:

Option (B):

• The solution will be lyophilic if the refractive indices of the dispersed phase and the dispersion medium are exactly the same magnitude.
• The Tyndall effect is substantially less in this case because the particles are fully solvated, reducing the difference in refractive indices between the two phases.
• The diameter of the particles should not match the wavelength of the light for efficient scattering.

Option (C):

• When refractive indices of the dispersed phase and the dispersion medium do not differ much in magnitude Tyndal effect is not seen.

Option (D):

• Option A is the correct option, so this option is ruled out.

Therefore, option (A) is correct.