Friday, April 11, 2008

Science of Color

Today we will talk about color, the most sensational aspect which makes life lively without which life could be a monotonus black and white picture.According to Maxwell, color is an electromagnetic wave of particular range of wavelength. We know that visible range of electromagnetic spectrum is from 380 to 750 nm. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. So we can say light/energy is wavelength (point A)White light is a bundle of electromagnetic wavelength of all colors. When white light falls on a prism the different colors or wavelength will be unbundled according to the refractive index of the prism. The electromagnetic waves are colorful according to the wavelength it carry but how come objects are having colors. Interesting?

Every object is this universe is made up of atoms which have its own nucleus and electrons revolve around it in shells and orbits. The shell in which the electrons revolve depends on the energy carried by the electron. When it gain energy from ambience and it tends to move to higher orbits which we call as higher energy level. As it loses some energy to the ambience it comes down to lower orbit. The stable state will be reached when electrons reach it ground level.

So electrons in an object absorb required energy i.e. wavelength (point A) to move from one level to another and thus it will reflect the rest of the wavelength. The color of the particular reflected wavelength appears to be the color of the object. The wavelength that got reflected depends on the atomic structure of the object. So obviously the color of any object will be decided by the atomic structure and energy level of electrons.

Chilly is red because it absorbs all wavelengths from white light apart from 625–740 nm which is the wavelength of color red. This concept suits for all the objects which are having color complexion.To prove this concept if you place a green leaf in red light which is nothing but a filtered vibration of 480-405 THz ,then leaf which will absorb all the red light will not be green any more as the light fall on it is not having the green wavelength.It’s quite evident that the color of the leaf will be black as all wavelengths have been absorbed by the leaf.

Now we know why iron is red as we heat it.
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