Question

The Tyndall effect is observed only when the following conditions are satisfied:

• (A) The diameter of the dispersed particle is much smaller than the wavelength of the light used.
• (B) The diameter of the dispersed particle is not much smaller than the wavelength of the light used.
• (C) The refractive indices of the dispersed phase and the dispersion medium differ greatly in magnitude.
• (D) The refractive indices of the dispersed phase and the dispersion medium are almost similar in magnitude.

• A. \(A\) and \(C\)
• B. \(A\) and \(D\)
• C. \(B\) and \(C\)
• D. \(B\) and \(D\)

Hint:

Understanding the physical properties like particle size and refractive index differences is crucial in predicting the behavior of colloidal systems under light.

Answer 1

The Correct Option is C

Step 1: Analyze the conditions necessary for the Tyndall effect.

The Tyndall effect occurs when light scatters as it passes through a colloid. The conditions for this to happen effectively include:

• (B) The particle size should be comparable to the wavelength of the light, not much smaller. This condition allows for sufficient scattering to be visible.
• (C) A significant difference in the refractive indices between the dispersed phase and the dispersion medium enhances the scattering effect, making it more pronounced.

Step 2: Determine the correct options based on the scattering requirements.

Both conditions \(B\) and \(C\) are necessary for the Tyndall effect to be observed, thus making the correct answer option (3).

Answer 2

To solve this question, we need to identify the conditions required for the Tyndall effect to be observed.

1. Understanding the Tyndall Effect:
The Tyndall effect refers to the scattering of light by particles in a colloid or suspension. For the Tyndall effect to be observed, certain conditions must be satisfied:
The particles in the colloidal suspension must be small enough to scatter light but large enough to create observable scattering.
The refractive index difference between the dispersed phase and the dispersion medium must be significant enough to cause light scattering.

2. Analyzing the Given Conditions:
Let's analyze the options:
(A) The diameter of the dispersed particles is much smaller than the wavelength of the light used. This is generally a requirement for the Tyndall effect to occur, as smaller particles scatter light more effectively.
(B) The diameter of the dispersed particles is not much smaller than the wavelength of the light used. This could lead to less scattering or no scattering at all.
(C) The refractive indices of the dispersed phase and the dispersion medium differ greatly. This is important for creating a noticeable scattering effect.
(D) The refractive indices of the dispersed phase and the dispersion medium are almost similar in magnitude. This would reduce the Tyndall effect, as the difference in refractive indices is what causes light to scatter. Thus, the conditions for the Tyndall effect are:
The diameter of the dispersed particles must be much smaller than the wavelength of the light (condition A).
The refractive indices of the dispersed phase and the dispersion medium must differ significantly (condition C).

Final Answer:
The correct answer is Option C: (A) and (C).