The sky looks blue due to ………… effect.

Answer

To answer the question "The sky looks blue due to ………… effect," we can follow these steps:

### Step 1: Identify the Effect
The sky appears blue due to a specific scattering phenomenon. The correct term to fill in the blank is "Tyndall effect."

### Step 2: Understand the Tyndall Effect
The Tyndall effect refers to the scattering of light by colloidal particles. This scattering makes the path of the light beam visible, which is why we can see the blue color in the sky.

### Step 3: Explain the Cause of the Tyndall Effect
The Tyndall effect occurs due to the scattering of light by particles that are suspended in a medium. In the case of the sky, the particles are tiny molecules in the atmosphere.

### Step 4: Factors Affecting Scattering
There are two main factors that influence the scattering of light:
1. **Wavelength of Light**: Different wavelengths of light scatter differently. Shorter wavelengths scatter more than longer wavelengths.
2. **Refractive Index**: The difference in the refractive index between the dispersed phase (air molecules) and the dispersion medium (the atmosphere) also plays a role.

### Step 5: Relate Wavelength to Color
The blue color of the sky is due to the fact that blue light has a shorter wavelength compared to other colors in the visible spectrum. Since scattering is inversely proportional to the wavelength, blue light scatters more effectively than other colors.

### Conclusion
Thus, the sky looks blue due to the Tyndall effect, which is the result of the scattering of shorter wavelengths of light (blue) by the particles in the atmosphere.

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