- Question Answer
- What is meant by scattering of light? The sky appears blue and the Sun appears reddish at sunrise and sunset
. What is meant by scattering of light? The sky appears blue and the Sun appears reddish at sunrise and sunset
Explain these phenomena with reason.
Ans. Scattering of light. The phenomenon of spreading of light when it falls on various types of suspended particles in its path is called scattering of light.
(i) The sky appears blue because of scattering of white light that takes place in the atmosphere. The molecules of air and other fine particles suspended in the atmosphere have a size smaller than the wavelength of visible light. So these particles scatter more effectively the light rays of shorter wavelength at the blue end than light rays of longer wavelengths at the red end. Thus, when sunlight passes through the atmosphere,. the fine particles in air scatter blue light. When the scattered blue light enters our eyes, it gives us the feeling of a blue sky.
(ii) The sun at sunrise and at sunset time is located very near to the horizon of the earth.
Hence light has to travel a long distance through the earth's atmosphere. Near the horizon most of the blue light of shorter wavelength is scattered away by the particles in the atmosphere. Therefore, the red light of longer wavelengths is least scattered by the air particles and is able to reach our eyes. This gives rise to the reddish appearance of the Sun at sunrise and sunset.