Question

Tyndall effect is applicable when :

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

Answer 1

Answer: (A), (D)

The correct options are
A the diameter of the dispersed particle is not much smaller than the wavelength of the light used
D the refractive indices of the dispersed phase and the dispersion medium differ greatly in magnitude

The Tyndall effect is the scattering of light as a light beam passes through a colloid. The individual suspension particles scatter and reflect light making the beam visible. The amount of scattering depends on the frequency of the light (the diameter of the dispersed particle is much higher than the wavelength of the light used and density of the particles). The refractive indices of the dispersed phase and the dispersion medium must differ greatly in magnitude.
Hence, options A and D are correct.