Which of the following phenomena is responsible for Tyndall effect? 

The correct answer is Scattering of light.

Key Points

• The Tyndall effect is a phenomenon where light is scattered by particles in a colloid or in a very fine suspension.
• It is named after the 19th-century physicist John Tyndall, who first studied the effect.
• The scattering of light by the particles causes the light beam to become visible, which is why we can see the path of a beam of sunlight entering a dusty room.
• This effect is most often observed when the diameter of the particles is in the range of 40 to 900 nanometers.

Additional Information

• Colloids
  • A colloid is a mixture where one substance of microscopically dispersed insoluble particles is suspended throughout another substance.
  • Examples include fog, milk, and jelly.
• Rayleigh Scattering
  • It is a phenomenon where particles much smaller than the wavelength of light cause the light to scatter.
  • It explains why the sky appears blue; shorter wavelengths (blue) are scattered more than longer wavelengths (red).
• Mie Scattering
  • This scattering occurs when the particles causing the scattering are of a size comparable to the wavelength of light being scattered.
  • Mie scattering explains the white appearance of clouds, where water droplets scatter all wavelengths of light equally.
• Applications of Tyndall Effect
  • Used in determining the size and density of particles in aerosols.
  • Applied in medical diagnostics, such as in detecting the presence of proteins in urine.