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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.

1. (i) and (iv)
2. (ii) and (iv)
3. (i) and (iii)
4. (ii) and (iii)

Correct answer: (ii) and (iv)

Solution

The Tyndall effect occurs when light is scattered by particles in a colloid or a fine suspension, which requires the particle size to be comparable to the wavelength of light (condition ii). Additionally, a significant difference in refractive indices (condition iv) enhances the scattering effect, making the Tyndall effect observable.

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