Today we will reveal what is the angle of refraction of an electromagnetic wave (the so-called light) and how its laws are formed.
Eye, skin, brain
Man has five basic senses. Medical scientists distinguish up to eleven different dissimilar sensations (for example, a feeling of pressure or pain). But people get basic information through their eyes. Up to ninety percent of the available facts, the human brain is aware of electromagnetic waves. So people mostly understand the beauty and aesthetics visually. The angle of refraction of light plays an important role in this.
Desert, lake, rain
The world around is riddled with sunlight. Air and water form the basis of what people like. Of course, there is its own severe beauty in arid desert landscapes, but mostly people still prefer a certain amount of moisture.
Man has always been fascinated by mountain streams and smooth plain rivers, calm lakes and ever-rolling waves of the sea, splashes of a waterfall and the cold sleep of glaciers. Not once did everyone notice the beauty of the play of light in the dew on the grass, the sparkling frost on the branches, the milky whiteness of the fog and the gloomy charms of low clouds. And all these effects are created due to the angle of refraction of the beam in the water.
Eye, electromagnetic scale, rainbow
Light is an oscillation of an electromagnetic field. The wavelength and frequency determines the form of the photon. The oscillation frequency depends on whether it is a radio wave, an infrared ray, a spectrum of some color visible to a person, ultraviolet, X-ray or gamma radiation. People are able to perceive with their eyes electromagnetic waves with a wavelength of 780 (red) to 380 (violet) nanometers. On the scale of all possible waves, this section occupies a very small area. That is, most of the electromagnetic spectrum, people are not able to perceive. And all the beauty accessible to man is created by the difference between the angle of incidence and the angle of refraction at the boundary of the media.
Vacuum, Sun, Planet
Photons are emitted by the sun as a result of a thermonuclear reaction. The fusion of hydrogen atoms and the birth of helium is accompanied by the ejection of a huge number of various particles, including light quanta. In a vacuum, electromagnetic waves propagate rectilinearly and at the highest possible speed. When it enters a transparent and denser environment, such as the atmosphere of the earth, light changes the speed of propagation. As a result of this, it changes the direction of propagation. How much determines the refractive index. The angle of refraction is calculated by Snell's formula.
Snell's Law
The Dutch mathematician Willebord Snell has worked with angles and distances all his life. He understood how to measure the distance between cities, how to find a given point in the sky. It is not surprising that he found a pattern of angles of refraction of light.
The formula of the law is as follows:
- n 1 sin θ 1 = n 2 sin θ 2 .
In this expression, characters have the following meanings:
- n 1 and n 2 are the refractive indices of one medium (from which the ray falls) and medium 2 (it enters into it);
- θ 1 and θ 2 are the angle of incidence and refraction of light, respectively.
Legislation Explained
It is necessary to give some explanations to this formula. By angles θ we mean the number of degrees that lies between the direction of the beam propagation and the normal to the surface at the point of contact of the light beam. Why is normal used in this case? Because in reality there are no strictly flat surfaces. And finding the normal to any curve is quite simple. Moreover, if the angle between the boundary of the media and the incident beam x is known in the problem, then the desired angle θ is only (90º-x).
Most often, light enters from a more rarefied (air) into a denser (water) medium. The closer the atoms of the medium are to each other, the more the beam is refracted. Therefore, the denser the medium, the greater the angle of refraction. But it happens the other way around: light falls from water to air or from air to vacuum. Under such circumstances, a condition may arise under which n 1 sin θ 1 > n 2 . That is, the entire beam will be reflected back to the first medium. This phenomenon is called total internal reflection. The angle at which the above circumstances occur is called the limiting angle of refraction.
What determines the refractive index?
This value depends only on the properties of the substance. For example, there are crystals for which it matters at what angle the beam enters. Anisotropy of properties is manifested in birefringence. There are media for which the polarization of the incoming radiation is important. It must also be remembered that the angle of refraction depends on the wavelength of the incident radiation. It is on this difference that experience with the separation of white light into a rainbow with a prism is based. It should be noted that the temperature of the medium also affects the refractive index of radiation. The faster the atoms of a crystal oscillate, the more strongly its structure and ability to change the direction of light propagation are deformed.
Examples of refractive index values
We give different values for familiar environments:
- Salt (the chemical formula of NaCl) as a mineral is called "halite." Its refractive index is 1.544.
- The angle of refraction of a glass is calculated from its refractive index. Depending on the type of material, this value ranges between 1.487 and 2.186.
- Diamond is famous precisely for the play of light in it. Jewelers take into account all its planes when cutting. The refractive index of diamond is 2.417.
- In water purified from impurities, the refractive index is 1.333. H 2 O is a very good solvent. Therefore, there is no chemically pure water in nature. Each well, each river is characterized by its composition. Consequently, the refractive index also changes. But to solve simple school problems, one can take such a value.
Jupiter, Saturn, Callisto
Until now, we talked about the beauty of the earthly world. The so-called normal conditions imply a very specific temperature and pressure. But there are other planets in the solar system. Different landscapes are familiar there.
On Jupiter, for example, it is possible to observe argon haze in methane clouds and ascending helium fluxes. Also there are familiar x-ray auroras.
On Saturn, ethane mists obscure the hydrogen atmosphere. On the lower layers of the planet, diamond rains come from very hot methane clouds.
At the same time, the rocky frozen satellite of Jupiter Callisto has an inland ocean rich in hydrocarbons. Perhaps sulfur-absorbing bacteria live in its bowels.
And in each of these landscapes, beauty is created by the play of light on different surfaces, faces, ledges and clouds.