Question

The effect that can be observed when sunlight passes through canopy of dense forest is

• A. scattering effect
• B. dispersion effect
• C. tyndall effect
• D. colloid effect % "colloid effect" is general, Tyndall is specific to colloids.

Hint:

- Tyndall Effect: The scattering of light as a light beam passes through a colloid. The individual suspension particles scatter and reflect light, making the beam visible. - Examples: Sunlight passing through a smoky room or a forest canopy (due to mist/dust), path of a projector beam in a dusty cinema hall. - It is used to distinguish between a true solution and a colloidal solution (true solutions do not show Tyndall effect as particles are too small).

Answer 1

The Correct Option is C

Step 1: Understand the phenomenon described.
When sunlight passes through the canopy of a dense forest, the tiny water droplets or dust particles suspended in the air (mist/haze within the forest) scatter the sunlight, making the path of light visible.

Step 2: Relate this to known optical effects.
- Scattering effect: This is a general term for the deflection of light by particles.
Rayleigh scattering (by particles much smaller than wavelength, like air molecules) causes the blue sky.
Mie scattering (by larger particles) is less wavelength-dependent.
- Dispersion effect: The splitting of white light into its constituent colors (spectrum) when it passes through a prism or a medium where the refractive index varies with wavelength.
Not the primary effect here.
- Tyndall effect: This is the scattering of a beam of light by particles in a colloid or a very fine suspension.
The individual suspension particles scatter and reflect light, making the beam visible.
The path of light through a colloidal solution is visible from the side.
This accurately describes what happens when sunlight passes through mist or dust in a forest canopy.
- Colloid effect: This is not a standard specific optical term; "Tyndall effect" is the specific effect observed in colloids and fine suspensions.

Step 3: Identify the most appropriate term.
The visibility of light beams passing through the forest canopy due to scattering by suspended particles (like mist or dust, which can form a colloidal dispersion in air) is a classic example of the Tyndall effect.
This matches option (3).