The colour of the clear sky is blue due to __________ of light by particles in the atmosphere of size ____________ than the wavelength of visible light.

Correct option is B

The correct answer is (b) scattering. smaller.

Explanation:

The color of the clear sky appears blue due to a phenomenon called Rayleigh scattering. This is the scattering of light by particles or molecules in the atmosphere that are much smaller than the wavelength of visible light.

How does Rayleigh scattering work?

• Sunlight is composed of light of many colors, corresponding to different wavelengths. When sunlight enters Earth's atmosphere, it interacts with molecules like nitrogen and oxygen, which are much smaller than the wavelength of visible light.

• Scattering occurs when light interacts with particles or molecules. The degree of scattering depends on the size of the particles and the wavelength of the light.

• Rayleigh scattering is most effective when the scattering particles are much smaller than the wavelength of the light. In this case, the particles are molecules in the air (such as nitrogen and oxygen), and their size is much smaller than the wavelength of visible light.

• According to Rayleigh's law, the amount of scattering is inversely proportional to the fourth power of the wavelength of light. This means that shorter wavelengths (like blue and violet light) scatter more than longer wavelengths (like red and yellow light).

Why does the sky appear blue?

• The blue light has a shorter wavelength (around 450–495 nanometers) compared to other visible colors (like red, which has a longer wavelength).

• Because of its shorter wavelength, blue light gets scattered in all directions by the air molecules, and this scattered blue light is what we see when we look up at the sky.

• Even though violet light is scattered more than blue, human eyes are more sensitive to blue light, and the upper atmosphere absorbs some violet light, so the sky appears blue rather than violet.