Tag: physics

The higher the wavelength the lesser the scattering. Yellow light has higher wavelength so it is least likely to be scattered among all colours in the visible region (except red & orange). So this light is visible from long distance even when there is foggy weather.

Among the constituent colours of white light, red has the longest wavelength and hence least frequency. As a result, red is least scattered among all colours. So, red colour reaches our eyes while all other colours scatter away during sun-rise and sun-set.

Red light is the least scattered by fine particles, fog or smoke present in the atmosphere which makes it easier to detect any danger clearly and distinctly.

A true solution does not have any fine particles dissolved in it which prevents scattering of light thus making it invisible.

The earths atmosphere is a heterogeneous mixture of minute particles like smoke, tiny water droplets, suspended particles of dust and molecules of air. When a beam of light strikes such fine particles, the path of the beam becomes visible. This phenomenon of scattering of light by the colloidal particles is called Tyndall effect.

The molecules of water and other fine particles in the atmosphere scatter light of shorter wavelengths at the blue end than light of longer wavelengths at the red end. Thus, when sunlight passes through water and air, the fine particles scatter the blue color more strongly than red. This scattered blue light enters our eyes and makes the ocean and sky appear blue. Near the horizon sunlight passes through thicker layers of air having larger particles that scatter light of longer wavelength such as the red end of the spectrum. Also it travels larger distance at horizon causing most of the light of shorter wavelength at the blue end of the spectrum to scatter away by the small particles of the atmosphere before reaching the earth.

Near the horizon sunlight passes through thicker layers of air having larger particles that scatter light of longer wavelength such as the red end of the spectrum. Also it travels larger distance at horizon before reaching the earth. However, light from the Sun overhead travels relatively shorter distance. At noon, the Sun appears white as only a little of the blue color is scattered whereas, near the horizon, most of the light of shorter wavelength at the blue end of the spectrum are scattered away by the small particles of the atmosphere. Therefore, the light that reaches our eyes is of longer wavelength which gives rise to the reddish appearance of the Sun.

Red light is the least scattered by fine particles, fog or smoke present in the atmosphere which makes it easier to detect it clearly and distinctly to avoid any obstruction.

When a beam of light passes through colloidal solution, it gets scattered causing the light beam to become visible. 

Fine particles scatter light of shorter wavelength at the blue end of the spectrum and larger particles scatter light of longer wavelength at the red end of the spectrum.