light beam passing through triangular prism, is deflected to the edge lying opposite the refracting angle of the prism.However, if it is a beam of white light, it is after the pass through the lens, not only rejected, but also decomposes on the colored beams.This phenomenon is called dispersion of light.It was first studied by Isaac Newton in 1666 in a series of remarkable experiments.
light source in the experiments of Newton was a small circular hole, located in the shuttered windows, illuminated by the rays of the sun.When the front of the hole was mounted prism on the wall instead of the circular spots appear colored line, called Newton range.Such Spector consists of seven main colors: red, orange, yellow, green, cyan, blue and purple, which are gradually into one another.Each of them has a different size range of space.Maximum length of a purple band, the smallest - red.
following experience has been that of a wide beam of colored rays obtained through the prism screen with a small hole stood out narrow beams of a certain color, and sent the second prism.
Prism rejecting them does not change the color of the light.Such rays are called simple or monochromatic (one color).
Experience shows that red rays feel less deviation compared with violet, iebeams of different color differently refracted prism.
collecting lens colored beams of rays coming out of the prism, Newton got a white screen instead of the colored stripes and white image of the hole.
Of all of these experiments, Newton made the following conclusions:
- white light on the nature of light is a complex that consists of colored rays;
- from light beams of different color and different refractive indices of the substance;as a result of this, when the white light beam is deflected prism, it is decomposed into a spectrum;
- if the United colored rays of the spectrum, you get white light again.
Thus, the dispersion of light - a phenomenon which is due to the dependence of refractive index of the wavelength (or frequency).
dispersion of light is celebrated not only when light passes through a prism, but also in various other cases, the refraction of light.In particular, in the breaking of the drops of water to sunlight followed by its decomposition into colored rays, it is explained the formation of a rainbow.
Newton spectrum for directing the prism is quite a cylindrical beam of sunlight through a round hole made in the shutter.
thus obtained spectrum is a series of different color images of round holes partially overlapping with each other.For a cleaner spectrum, the study of the phenomenon of the dispersion of light, Newton suggested not to use a round hole, a narrow slit parallel to the refracting edge of the prism.With the lens on the screen is a clear image of the slit, and then set the prism behind the lens that gives the spectrum.
most clean and bright spectra were obtained with the help of special devices - spectroscopy and spectrographs.
absorption of light - a phenomenon in which the energy of the light wave is reduced by eѐ passing through matter.This is due to the conversion of wave energy into light energy of the secondary radiation, or in other words, the internal energy of the material which has a different spectral composition and the other direction of propagation.
absorption of light can cause heating of the substance, ionization or excitation of molecules or atoms, photochemical reactions and other processes in the material.
