Why do you see bright rays of sunlight when it passes through small gaps between the leaves of a dense tree?
We see bright rays of sunlight passing through small gaps between the leaves of a dense tree due to the Tyndall effect. This is the scattering of light by particles present in the air.
When sunlight passes through the gaps, it forms a fine beam. The air contains dust and smoke particles which scatter this light, making the path of the beam clearly visible to us.
This scattering of light occurs because the air acts like a colloid or a suspension containing dispersed particles, rather than a transparent solution where the path of light would not be visible.
Explanation
The textbook explains this everyday observation as the Tyndall effect. When sunlight filters through small gaps, it acts like a fine beam of light entering a dark room. The air contains dust and smoke particles that act as the dispersed phase of a colloid or suspension. These particles scatter the light, making the beam's path visible, unlike in a transparent solution where scattering does not occur.