Physical term "spectrum" is derived from the Latin word spectrum, which means "vision", or even "ghost".
But the thing called such a grim word, is of direct relevance to this beautiful natural phenomenon, like a rainbow.
Broadly spectrum calleddistribution of values of a physical quantity. A special case - the distribution of frequencies of electromagnetic radiation. The light that is perceived by the human eye - it is also a type of electromagnetic radiation, and has a spectrum.
Opening of the spectrum
The honor of opening the spectrum of light belongs to I.Newton. Getting to this study, the researchers pursued a practical purpose: to improve the quality of lenses for telescopes. The problem was that the edge of the image, which can be seen in the telescope, painted in all colors of the rainbow.
AND.Newton put the experience: in a darkened room through a small hole penetrating beam of light that fell on the screen. But on the way it was set triangular glass prism. On the screen was designated rainbow stripe instead of white light spot. White sunlight was harder compound.
Scientist complicated experience. He became prodelyvat to screen small holes to pass through them only one color beam (for example, red), and behind the screen installed a second prism and another screen. It was found that colored rays that are spread out light first prism, do not decompose into its constituent parts, passing through the second prism, they just rejected. Consequently, these light beams are simple and they are refracted in the prism in different ways, making it possible to "spread out" on a part of the light.
So it became clear that different colors do not occurfrom different degrees of "mixing of light and darkness," as it was believed to Isaac Newton, and are integral parts of the world. This composition was named light spectrum.
I. OpeningNewton has been important for its time, it has given much study of the nature of light. But the real revolution in science associated with the study of the spectrum of light, occurred in the middle of the XIX century.
German scientists R.V.Bunzen and GRKirchhoff studied the spectrum of light emitted by the fire, which mixed with the evaporation of various salts. Spectrum varied depending on impurities. This led researchers to believe that the light spectrum can be judged on the chemical composition of the Sun and other stars. Thus was born the spectral analysis method.
This discovery was important not only forphysics, chemistry, astronomy, and philosophy - in the matter of understanding the world. While many philosophers have believed that the world is a phenomenon know that until the end of man is not able to. As an example, the sun and the stars that can be observed, we can calculate their weight, size, and distance to them, but to study their chemical composition can not be. With the advent of the spectral analysis of this characteristic of stars ceased to be unknowable, and therefore, the idea is unknowable world has been questioned.