Question

Which of the following is true according to the definition of Tyndall effect?

• A. In a light source containing many wavelengths, the larger wavelengths are relatively scattered more
• B. In a light source containing many wavelengths, the smaller wavelengths are relatively scattered more
• C. In a light source containing many wavelengths, the wavelengths wavelengths in the middle are relatively scattered more
• D. All the wavelengths are scattered equally

Answer 1

The correct option is D All the wavelengths are scattered equally

Colloidal dispersions can be easily distinguished from true solutions by their light-scattering properties. The nature of this scattering largely depends on the ratio of the size of the dispersed phase to the wavelength of the light. The particles in the colloid tend to scatter all wavelengths equally and this phenomenon is called Tyndall Scattering.
In fact, the white colour of fog and milk are chiefly attributed to Tyndall scattering. The butterfat droplets in milk are actually transparent, but the scattering disperses the light in all directions so extensively that we are not that seeing through milk.