Question

When sunlight passes through the window of the classroom, the path of the light is visible. What is this effect called? Give reason.

Answer 1

This effect is called Tyndall effect.

The air in the classroom is a heterogeneous mixture of minute particles. These particles include suspended particles of dust, molecules of air and tiny water droplets. So it is a colloid. When a beam of light strikes such fine particles, the path of the beam becomes visible. The light reaches us, after being reflected diffusely by these particles. This phenomenon is a special case of scattering light by the colloidal particles, known as Tyndall effect.

This phenomenon is seen when sunlight passes through the window of the classroom. Thus, scattering of light makes the particles visible, giving rise to Tyndall effect.