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 main senses. Medical scientists distinguish up to eleven different dissimilar sensations (for example, a feeling of pressure or pain). But people get most of their information through their eyes. Up to ninety percent of the available facts the human brain is aware of as electromagnetic vibrations. So people mostly understand beauty and aesthetics visually. The angle of refraction of light plays an important role in this.
Desert, lake, rain
The world around is permeated with sunlight. Air and water form the basis of what people like. Of course, there is a harsh beauty to arid desert landscapes, but mostly people prefer some moisture.
Man has always been fascinated by mountain streams and smooth lowland rivers, calm lakes and ever-rolling waves of the sea, splashes of a waterfall and a cold dream of glaciers. More than once everyone has noticed the beauty of the play of light in the dew on the grass, the sparkle of hoarfrost on the branches, the milky whiteness of the fog and the gloomy beauty of low clouds. And all these effects are createdthanks to the angle of refraction of the beam in the water.
Eye, electromagnetic scale, rainbow
Light is a fluctuation of the electromagnetic field. The wavelength and its frequency determine the type of photon. The vibration frequency determines whether it will be a radio wave, an infrared ray, a spectrum of some color visible to a person, ultraviolet, X-ray or gamma radiation. Humans are able to perceive with their eyes electromagnetic vibrations with wavelengths ranging from 780 (red) to 380 (violet) nanometers. On the scale of all possible waves, this section occupies a very small area. That is, people are not able to perceive most of the electromagnetic spectrum. 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 between 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 release of a huge number of various particles, including light quanta. In a vacuum, electromagnetic waves propagate in a straight line and at the highest possible speed. When it enters a transparent and denser medium, such as the earth's atmosphere, light changes its propagation speed. As a result, it changes the direction of propagation. How much determines the refractive index. The angle of refraction is calculated using the Snell formula.
Snell's Law
Dutch mathematician Willebrord Snell worked all his life with angles and distances. He understood how to measure distances between cities, how to find a givenpoint in the sky. No wonder he found a pattern in the angles of light refraction.
The law formula looks like this:
- 1sin θ1 =n2sin θ2.
In this expression, the characters have the following meaning:
- 1 and n2 are the refractive indices of medium one (from which the beam falls) and medium 2 (it enters it);
- θ1 and θ2 are the angle of incidence and refraction of light, respectively.
Explanations to the law
It is necessary to give some explanations to this formula. Angles θ mean the number of degrees that lies between the direction of propagation of the beam 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. In addition, if the angle between the media boundary and the incident beam x is known in the problem, then the required angle θ is just (90º-x).
Most often, light enters from a more rarefied (air) to a denser (water) medium. The closer the atoms of the medium are to each other, the stronger the beam is refracted. Therefore, the denser the medium, the greater the angle of refraction. But it also happens the other way around: light falls from water into air or from air into a vacuum. Under such circumstances, a condition may arise under which n1sin θ1>n2. That is, the entire beam will be reflected back to the first medium. This phenomenon is called total internalreflection. The angle at which the circumstances described above 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. The 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 the experiment with the division of white light into a rainbow by a prism is based. It should be noted that the temperature of the medium also affects the refractive index of the radiation. The faster the atoms of a crystal vibrate, the more its structure and the ability to change the direction of light propagation are deformed.
Examples of the value of the refractive index
We give different values for familiar environments:
- S alt (chemical formula NaCl) as a mineral is called "halite". Its refractive index is 1.544.
- The angle of refraction of glass is calculated from its refractive index. Depending on the type of material, this value varies 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.
- Water purified from impurities has a refractive index of 1.333. H2O is a very good solvent. Therefore, there is no chemically pure water in nature. Every well, every river is characterizedwith its composition. Therefore, the refractive index also changes. But to solve simple school problems, you can take this value.
Jupiter, Saturn, Callisto
Until now, we have been talking 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. There are quite different landscapes.
On Jupiter, for example, it is possible to observe argon haze in methane clouds and helium updrafts. X-ray auroras are also common there.
On Saturn, ethane fogs cover the hydrogen atmosphere. On the lower layers of the planet, diamond rains from very hot methane clouds.
However, Jupiter's rocky frozen moon Callisto has an internal ocean rich in hydrocarbons. Perhaps sulfur-consuming bacteria live in its depths.
And in each of these landscapes, the play of light on different surfaces, edges, ledges and clouds creates beauty.
