Monday, May 18, 2009


On incidence of white light on an object, some light gets absorbed and some gets scattered or reflected. Depending on the colors of the light it reflects or scatter, the object appears to have specific color. If the white light is completely reflected as from a smooth surface, the object would appear white even if the object bears a particular color in the light transmitted through it. Because of the fact that water is transparent to white light, it does not absorb light of any color; so the spot of water surface appear white. A similar observation is experimented while looking at water spray of a fountain or garden spray in the sun light, where some of the droplets appear white while others transparent. The cloud is collection of tiny water droplets formed by condensation of water molecules in the atmosphere. Because of the highly curved surface of droplets have, sunlight gets reflected from their surface in all directions.
The light rays can penetrate the water droplets at different angles and due to the difference in the refractive index for light of different color, white light splits to light rays of different color. This happens from all droplets and in all directions, because of multiple reflection of the dispersed light inside the droplets; the rainbow appears in the different location than that of droplets. But, as the white cloud consists of very fine droplets in high number density, the dispersed light recombines to white light along with the reflected light make the cloud appear white.

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