Dispersion is a rainbow?

In life, we are constantly confronted with the variance, but we do not always notice it or even sometimes do not know what it is. Now we will try to consider in more detail what the dispersion is. The first vivid example of this is the usual rainbow. There is hardly anyone who would never admire this beautiful phenomenon. According to an old legend, at the foot of the rainbow you can find a pot full of gold. We are so used to seeing the rainbow that it seems ordinary to us, and we do not understand its nature. In fact, each of its appearance is accompanied by complex physical processes, with which we will try to understand this article.

In the most general sense, dispersion is the refraction of light. Passing through the prism, the ray of light is refracted and disintegrates into different colors. This can be easily checked at home. We will make a small experiment. On a sunny day, it is necessary to close the window with a dense curtain and make a small hole in it, through which a narrow ray will penetrate into the room. On the opposite wall from this beam a bright spot will form. We put in the path of the beam a glass prism. Now we can see that the variance is the condition for the appearance of the rainbow, because the stain on the wall has become multicolored. In it you can see all the colors of the rainbow, from red to purple.

Thus, dispersion is an optical phenomenon caused by the dependence of the refractive index of a substance on the frequency of light (wavelength) or the dependence of the phase velocity of light waves on its frequency or wavelength. The consequence of the dispersion is the expansion of the light beam into the spectrum as it passes through the glass prism. The dispersion of light was discovered in 1672 by Newton, who was actively studying the spectrum.

Newton was not the first to conduct similar experiments. Already at the beginning of our era, it was known about the decomposition of light into a spectrum as it passed through large single crystals. The first researchers of the refraction of light were the English scientist T. Hariot and the Czech natural scientist J. Marci, but it was Newton who began to seriously analyze this process.

Newton conducted a whole complex of experiments and experiments with prisms. The results of his research were described in detail in "Lectures on Optics", "Optics" and "Theory of Light and Colors". Newton was able to prove that white light is not at all basic for all others, but on the contrary - it is not homogeneous. Different types of dispersion, that is, the decomposition of white light into its constituent parts, appear when the beam passes through various prisms and prism groups. Decay of light occurs because each color has a certain degree of refraction. Each color has its own specific properties. Dispersions clearly show their difference. The researches performed by scientists are of great interest for modern physicists in terms of not only the results, but also the methodology. Starting his research, Newton set the task not to put forward hypotheses, but to explain the properties of light by facts and reasoning. The scientist put a lot of experiments, noting that "the abundance of experiments does not interfere".

By sending a beam of light onto a glass prism, Newton was able to see a kind of rainbow on the screen. The scientist singled out seven primary colors, which we all now know well. Why seven? It was the seven colors that were most striking. In addition, in music, too, only seven notes, but their variations allow you to create real works of art, unlike each other. Then he conducted a reverse experiment, sending the spectrum to the edge of another glass prism. This again turned white light. As a result, Newton came up with the idea of creating a circle with seven sectors of different colors, during which the rotation will again get a white light.

Thus, dispersion is a complex physical process, conditioned by the properties of light and color. And it is thanks to this process that we can observe a rainbow after a storm. Now you have an idea from the scientific point of view about the reasons for the appearance of the rainbow.