Question

When a strong beam of light is passed through a colloidal solution, the light will ________.
1. be scattered
2. pass unchanged
3. be absorbed
4. be reflected

Answer 1

Correct Answer - Option 1 : be scattered

The correct answer is be scattered.

• When a beam of light is passed through a colloidal sol, colloidal particles scatter light and we can see the path of light. Thus, the Tyndall effect is observed.
• Tyndall Effect: 
  • ​The Tyndall effect is the phenomenon in which the particles in a colloid scatter the beams of light that are directed at them. This effect is exhibited by all colloidal solutions and some very fine suspensions. Therefore, it can be used to verify if a given solution is a colloid. The intensity of scattered light depends on the density of the colloidal particles as well as the frequency of the incident light.
  • When a beam of light passes through a colloid, the colloidal particles present in the solution do not allow the beam to completely pass through. The light collides with the colloidal particles and is scattered (it deviates from its normal trajectory, which is a straight line). This scattering makes the path of the light beam visible.

• Examples of the Tyndall Effect:
  • Milk is a colloid that contains globules of fat and protein. When a beam of light is directed at a glass of milk, the light is scattered. This is a great example of the Tyndall effect.
  • When a torch is switched on in a foggy environment, the path of the light becomes visible. In this scenario, the water droplets in the fog are responsible for the light scattering.
  • Opalescent glass has a bluish appearance when viewed from the side. However, orange-colored light emerges when light is shined through the glass.