Tyndall effect is shown by particles in colloidal solutions and very fine suspensions that can scatter a beam of light passing through them.

Quick Scoop: Core Idea

  • Tyndall effect = scattering of light by tiny particles in a mixture, making the path of the light beam visible.
  • This happens when the dispersed particles are of colloidal size (roughly nanometer scale, smaller than or comparable to the wavelength of visible light).

So, in the language of typical exam options:

✅ Tyndall effect is shown by:

  • particles in a colloidal solution
  • particles in a very fine suspension

Not by:

  • true solutions (like salt in water) → particles are too small to scatter light.
  • large particles (like stones, sand grains) → they don’t form a colloid; light is blocked or simply reflected, not a classic Tyndall effect.

Everyday examples (for memory)

  • A beam of light visible in fog or mist (headlights in fog, torch in mist).
  • Light through milk or soapy water, where the beam becomes visible.
  • Blue appearance of some colloids like opalescent glass or certain smoke.

Exam-style final answer:
Tyndall effect is shown by particles in colloidal solutions and very fine suspensions (both A and B).

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