Question

Due to which phenomenon of light does the sky appear blue?

• A. Reflection
• B. Refraction
• C. Dispersion
• D. Scattering

Hint:

Shorter wavelengths of light (like blue) scatter more than longer wavelengths (like red). This is why the sky appears blue and the sunset appears reddish.

Answer 1

The Correct Option is D

Step 1: Understanding the phenomenon.
When sunlight enters the Earth's atmosphere, it interacts with the air molecules and dust particles. These particles scatter the light in all directions. This scattering is more effective for shorter wavelengths (blue and violet light) than for longer wavelengths (red and orange light).
Step 2: Reason for blue color of the sky.
Although violet light is scattered even more, our eyes are more sensitive to blue light and part of violet is absorbed by the upper atmosphere. Hence, the sky appears blue to us.
Step 3: Analysis of options.
(A) Reflection: This occurs when light bounces off a surface — not responsible for the blue color of the sky.
(B) Refraction: This is bending of light through a medium; unrelated to sky color.
(C) Dispersion: It causes splitting of light into colors (as in a prism), but doesn’t explain the blue sky.
(D) Scattering: Correct — scattering of light (Rayleigh scattering) causes the blue color of the sky.
Step 4: Conclusion.
Hence, the blue color of the sky is due to the scattering of sunlight by air molecules.