Explain how the colour of the scattered light depends on the size of the colloidal particles.

Explanation

The size of the scattering particles decides the wavelength of the light which they scatter and hence, the colour of the scattered light. Smaller particles such as air molecules in the atmosphere having sizes less than the wavelength of visible light mainly scatter blue light of shorter wavelengthin the visible spectrum. The particles of relatively larger size scatter light of longer wavelengths [near red end of the spectrum]. The large particles like raindrops, dust and ice scatter white light. This makes the clouds appear white.