Abstract on physics on the topic: Read radiation. Radiation: its types and effects on the body What is radiation in physics

Today we’ll talk about what radiation is in physics. Let's talk about the nature of electronic transitions and give an electromagnetic scale.

Deity and atom

The structure of matter became a subject of interest to scientists more than two thousand years ago. Ancient Greek philosophers asked questions about how air differs from fire, and earth from water, why marble is white and coal is black. They created complex systems of interdependent components, refuted or supported each other. And the most incomprehensible phenomena, for example, a lightning strike or sunrise, were attributed to the action of the gods.

Once, after observing the steps of the temple for many years, one scientist noticed: each foot that stands on a stone carries away a tiny particle of matter. Over time, the marble changed shape and sagged in the middle. The name of this scientist is Leucippus, and he called the smallest particles atoms, indivisible. This began the path to studying what radiation is in physics.

Easter and light

Then dark times came and science was abandoned. Everyone who tried to study the forces of nature was dubbed witches and sorcerers. But, oddly enough, it was religion that gave impetus to the further development of science. The study of what radiation is in physics began with astronomy.

The time for celebrating Easter was calculated differently each time in those days. The complex system of relationships between the vernal equinox, the 26-day lunar cycle and the 7-day week prevented the compilation of date tables for the celebration of Easter for more than a couple of years. But the church had to plan everything in advance. Therefore, Pope Leo X ordered the compilation of more accurate tables. This required careful observation of the movements of the Moon, stars and Sun. And in the end, Nicolaus Copernicus realized: the Earth is not flat and not the center of the universe. A planet is a ball that revolves around the Sun. And the Moon is a sphere in Earth's orbit. Of course, one might ask, “What does all this have to do with what radiation is in physics?” Let's reveal it now.

Oval and beam

Later, Kepler supplemented the Copernican system by establishing that the planets move in oval orbits, and this movement is uneven. But it was precisely that first step that instilled in humanity an interest in astronomy. And there it was not far from the questions: “What is a star?”, “Why do people see its rays?” and “How does one luminary differ from another?” But first you will have to move from huge objects to the smallest. And then we come to radiation, a concept in physics.

Atom and raisin

At the end of the nineteenth century, sufficient knowledge had accumulated about the smallest chemical units of matter - atoms. They were known to be electrically neutral, but to contain both positively and negatively charged elements.

Many assumptions have been made: that positive charges are distributed in a negative field, like raisins in a bun, and that an atom is a drop of dissimilarly charged liquid parts. But Rutherford's experience clarified everything. He proved that at the center of the atom there is a positive heavy nucleus, and around it there are light negative electrons. And the configuration of the shells is different for each atom. This is where the peculiarities of radiation in the physics of electronic transitions lie.

Boron and orbit

When scientists found out that the light negative parts of the atom are electrons, another question arose - why they do not fall onto the nucleus. After all, according to Maxwell’s theory, any moving charge radiates, and therefore loses energy. But atoms existed as long as the universe, and were not going to annihilate. Bohr came to the rescue. He postulated that electrons are in certain stationary orbits around the atomic nucleus, and can only be in them. The transition of an electron between orbits is carried out by a jerk with the absorption or emission of energy. This energy could be, for example, a quantum of light. In essence, we have now outlined the definition of radiation in particle physics.

Hydrogen and photography

Initially, photography technology was invented as a commercial project. People wanted to remain for centuries, but not everyone could afford to order a portrait from an artist. And photographs were cheap and did not require such a large investment. Then the art of glass and silver nitrate put military affairs into its service. And then science began to take advantage of photosensitive materials.

Spectra were photographed first. It has long been known that hot hydrogen emits specific lines. The distance between them obeyed a certain law. But the spectrum of helium was more complex: it contained the same set of lines as hydrogen, and one more. The second series no longer obeyed the law derived for the first series. Here Bohr's theory came to the rescue.

It turned out that there is only one electron in a hydrogen atom, and it can move from all higher excited orbits to one lower one. This was the first series of lines. Heavier atoms are more complex.

Lens, grating, spectrum

This marked the beginning of the use of radiation in physics. Spectral analysis is one of the most powerful and reliable ways to determine the composition, quantity and structure of a substance.

1. The electron emission spectrum will tell you what is contained in the object and what the percentage of a particular component is. This method is used in absolutely all areas of science: from biology and medicine to quantum physics.
2. The absorption spectrum will tell you which ions and in which positions are present in the lattice of the solid.
3. The rotational spectrum will demonstrate how far apart the molecules are inside the atom, how many and what kind of bonds each element has.

And the ranges of application of electromagnetic radiation are countless:

• radio waves explore the structure of very distant objects and the interior of planets;
• thermal radiation will tell about the energy of processes;
• visible light will tell you in which directions the brightest stars lie;
• ultraviolet rays will make it clear that high-energy interactions are occurring;
• The X-ray spectrum itself allows people to study the structure of matter (including the human body), and the presence of these rays in cosmic objects will notify scientists that there is a neutron star, a supernova explosion or a black hole at the focus of the telescope.

Pure black body

But there is a special section that studies what thermal radiation is in physics. Unlike atomic light, thermal emission of light has a continuous spectrum. And the best model object for calculations is an absolutely black body. This is an object that “catches” all the light falling on it, but does not release it back. Oddly enough, a completely black body emits radiation, and the maximum wavelength will depend on the temperature of the model. In classical physics, thermal radiation gave rise to a paradox. It turned out that any heated thing should radiate more and more energy until, in the ultraviolet range, its energy would destroy the universe.

Max Planck was able to resolve the paradox. He introduced a new quantity, quantum, into the radiation formula. Without giving it any special physical meaning, he discovered a whole world. Now quantization of quantities is the basis of modern science. Scientists realized that fields and phenomena consist of indivisible elements, quanta. This led to deeper studies of matter. For example, the modern world belongs to semiconductors. Previously, everything was simple: metal conducts current, other substances are dielectrics. And substances such as silicon and germanium (semiconductors) behave incomprehensibly in relation to electricity. To learn how to control their properties, it was necessary to create an entire theory and calculate all the possibilities of p-n junctions.

You are well aware that the main source of heat on Earth is the Sun. How is heat transferred from the Sun? After all, the Earth is located at a distance of 15 10 7 km from it. All this space outside our atmosphere contains very rarefied matter.

As is known, in a vacuum, energy transfer by thermal conduction is impossible. It cannot occur due to convection either. Therefore, there is another type of heat transfer.

Let's study this type of heat transfer through experiment.

Let's connect the liquid pressure gauge using a rubber tube to the heat sink (Fig. 12).

If you bring a piece of metal heated to a high temperature to the dark surface of the heat sink, the liquid level in the pressure gauge elbow connected to the heat sink will decrease (Fig. 12, a). Obviously, the air in the heat sink has heated up and expanded. The rapid heating of the air in the heat sink can only be explained by the transfer of energy to it from the heated body.

Rice. 12. Transfer of energy by radiation

Energy in this case was not transferred by thermal conductivity. After all, between the heated body and the heat sink there was air - a poor conductor of heat. Convection cannot be observed here either, since the heat sink is located next to the heated body and not above it. Hence, in this case, energy transfer occurs throughradiation.

Energy transfer by radiation is different from other types of heat transfer. It can be carried out in a complete vacuum.

All bodies emit energy: both highly heated and weakly heated ones, for example, the human body, a stove, an electric light bulb, etc. But the higher the temperature of a body, the more energy it transmits by radiation. In this case, the energy is partially absorbed by surrounding bodies, and partially reflected. When energy is absorbed, bodies heat up differently, depending on the state of the surface.

If you turn the heat receiver to the heated metal body, first with the dark side and then with the light side, then the liquid column in the pressure gauge elbow connected to the heat receiver will decrease in the first case (see Fig. 12, a), and in the second (Fig. 12, b) will rise. This shows that bodies with a dark surface absorb energy better than bodies with a light surface.

At the same time, bodies with a dark surface cool faster by radiation than bodies with a light surface. For example, in a light kettle, hot water retains a high temperature longer than in a dark one.

The ability of bodies to absorb radiation energy differently is used in practice. Thus, the surface of airborne weather balloons and airplane wings are painted with silver paint so that they are not heated by the sun. If, on the contrary, it is necessary to use solar energy, for example, in instruments installed on artificial Earth satellites, then these parts of the instruments are painted dark.

Questions

1. How to experimentally demonstrate the transfer of energy by radiation?
2. Which bodies absorb radiation energy better and which worse?
3. How does a person take into account in practice the different abilities of bodies to absorb radiation energy?

Exercise 5

1. In the summer, the air in the building is heated, receiving energy in various ways: through the walls, through an open window into which warm air enters, through glass that allows solar energy to pass through. What type of heat transfer are we dealing with in each case?
2. Give examples showing that bodies with a dark surface are heated more strongly by radiation than those with a light surface.
3. Why can it be argued that energy cannot be transferred from the Sun to the Earth by convection and thermal conduction? How is it transmitted?

Exercise

Using an outdoor thermometer, measure the temperature first on the sunny side of the house, then on the shady side. Explain why thermometer readings differ.

This is interesting...

Thermos. It is often necessary to keep food hot or cold. To prevent the body from cooling or heating, you need to reduce heat transfer. At the same time, they strive to ensure that energy is not transferred by any type of heat transfer: thermal conductivity, convection, radiation. A thermos is used for these purposes (Fig. 13).

Rice. 13. Thermos device

It consists of a 4 glass vessel with double walls. The inner surface of the walls is covered with a shiny metal layer, and air is pumped out from the space between the walls of the vessel. The space between the walls, devoid of air, conducts almost no heat. The metal layer, reflecting, prevents the transfer of energy by radiation. To protect the glass from damage, the thermos is placed in a special metal or plastic case 3. The vessel is sealed with a stopper 2, and a cap 1 is screwed on top.

Heat transfer and flora. In nature and human life, the plant world plays an extremely important role. The life of all living things on Earth is impossible without water and air.

Temperature changes constantly occur in the layers of air adjacent to the Earth and soil. The soil heats up during the day as it absorbs energy. At night, on the contrary, it cools down and releases energy. Heat exchange between soil and air is influenced by the presence of vegetation, as well as weather. Soil covered with vegetation is poorly heated by radiation. Strong cooling of the soil is also observed on clear, cloudless nights. Radiation from the soil goes freely into space. In early spring, frosts occur on such nights. During cloudy periods, the loss of soil energy by radiation is reduced. The clouds serve as a screen.

Greenhouses are used to increase soil temperature and protect crops from frost. Glass frames or those made of film transmit solar radiation (visible) well. During the day the soil warms up. At night, glass or film transmits invisible radiation from the soil less easily. The soil doesn't freeze. Greenhouses also prevent the upward movement of warm air - convection.

As a result, the temperature in greenhouses is higher than in the surrounding area.

Previously, people, in order to explain what they did not understand, came up with various fantastic things - myths, gods, religion, magical creatures. And although a large number of people still believe in these superstitions, we now know that there is an explanation for everything. One of the most interesting, mysterious and amazing topics is radiation. What is it? What types of it exist? What is radiation in physics? How is it absorbed? Is it possible to protect yourself from radiation?

general information

So, the following types of radiation are distinguished: wave motion of the medium, corpuscular and electromagnetic. Most attention will be paid to the latter. Regarding the wave motion of the medium, we can say that it arises as a result of the mechanical movement of a certain object, which causes a successive rarefaction or compression of the medium. Examples include infrasound or ultrasound. Corpuscular radiation is a flow of atomic particles such as electrons, positrons, protons, neutrons, alpha, which is accompanied by natural and artificial decay of nuclei. Let's talk about these two for now.

Influence

Let's consider solar radiation. This is a powerful healing and preventive factor. The set of accompanying physiological and biochemical reactions that occur with the participation of light is called photobiological processes. They take part in the synthesis of biologically important compounds, serve to obtain information and orientation in space (vision), and can also cause harmful consequences, such as the appearance of harmful mutations, the destruction of vitamins, enzymes, and proteins.

About electromagnetic radiation

In the future, the article will be devoted exclusively to him. What does radiation do in physics, how does it affect us? EMR is electromagnetic waves that are emitted by charged molecules, atoms, and particles. Large sources can be antennas or other radiating systems. The wavelength of the radiation (oscillation frequency) together with the sources is of decisive importance. So, depending on these parameters, gamma, x-ray, and optical radiation are distinguished. The latter is divided into a number of other subspecies. So, this is infrared, ultraviolet, radio radiation, as well as light. The range is up to 10 -13. Gamma radiation is generated by excited atomic nuclei. X-rays can be obtained by decelerating accelerated electrons, as well as by their transition from non-free levels. Radio waves leave their mark as they move alternating electric currents along the conductors of radiating systems (for example, antennas).

About ultraviolet radiation

Biologically, UV rays are the most active. If they come into contact with the skin, they can cause local changes in tissue and cellular proteins. In addition, the effect on skin receptors is recorded. It affects the whole organism in a reflex way. Since it is a nonspecific stimulator of physiological functions, it has a beneficial effect on the body’s immune system, as well as on mineral, protein, carbohydrate and fat metabolism. All this manifests itself in the form of a general health-improving, tonic and preventive effect of solar radiation. It is worth mentioning some specific properties that a certain wave range has. Thus, the influence of radiation on a person with a length of 320 to 400 nanometers contributes to the erythema-tanning effect. In the range from 275 to 320 nm, weakly bactericidal and antirachitic effects are recorded. But ultraviolet radiation from 180 to 275 nm damages biological tissue. Therefore, caution should be exercised. Prolonged direct solar radiation, even in the safe spectrum, can lead to severe erythema with swelling of the skin and a significant deterioration in health. Up to increasing the likelihood of developing skin cancer.

Reaction to sunlight

First of all, infrared radiation should be mentioned. It has a thermal effect on the body, which depends on the degree of absorption of rays by the skin. The word “burn” is used to describe its effect. The visible spectrum affects the visual analyzer and the functional state of the central nervous system. And through the central nervous system and onto all human systems and organs. It should be noted that we are influenced not only by the degree of illumination, but also by the color range of sunlight, that is, the entire spectrum of radiation. Thus, color perception depends on the wavelength and influences our emotional activity, as well as the functioning of various body systems.

Red color excites the psyche, enhances emotions and gives a feeling of warmth. But it quickly tires, contributes to muscle tension, increased breathing and increased blood pressure. Orange evokes a feeling of well-being and cheerfulness, while yellow lifts the mood and stimulates the nervous system and vision. Green is calming, useful during insomnia, fatigue, and improves the overall tone of the body. The color violet has a relaxing effect on the psyche. Blue calms the nervous system and keeps muscles toned.

A small retreat

Why, when considering what radiation is in physics, do we talk mostly about EMR? The fact is that this is precisely what is meant in most cases when the topic is addressed. The same corpuscular radiation and wave motion of the medium is an order of magnitude smaller in scale and known. Very often, when they talk about types of radiation, they mean exclusively those into which EMR is divided, which is fundamentally wrong. After all, when talking about what radiation is in physics, attention should be paid to all aspects. But at the same time, emphasis is placed on the most important points.

About radiation sources

We continue to consider electromagnetic radiation. We know that it represents waves that arise when an electric or magnetic field is disturbed. This process is interpreted by modern physics from the point of view of the theory of wave-particle duality. Thus, it is recognized that the minimum portion of EMR is a quantum. But at the same time, it is believed that it also has frequency-wave properties, on which the main characteristics depend. To improve the ability to classify sources, different emission spectra of EMR frequencies are distinguished. So this:

1. Hard radiation (ionized);
2. Optical (visible to the eye);
3. Thermal (aka infrared);
4. Radio frequency.

Some of them have already been considered. Each radiation spectrum has its own unique characteristics.

Nature of the sources

Depending on their origin, electromagnetic waves can arise in two cases:

1. When there is a disturbance of artificial origin.
2. Registration of radiation coming from a natural source.

What can you say about the first ones? Artificial sources most often represent a side effect that occurs as a result of the operation of various electrical devices and mechanisms. Radiation of natural origin generates the Earth’s magnetic field, electrical processes in the planet’s atmosphere, and nuclear fusion in the depths of the sun. The degree of electromagnetic field strength depends on the power level of the source. Conventionally, the radiation that is recorded is divided into low-level and high-level. The first ones include:

1. Almost all devices equipped with a CRT display (such as a computer).
2. Various household appliances, from climate control systems to irons;
3. Engineering systems that provide electricity supply to various objects. Examples include power cables, sockets, and electricity meters.

High-level electromagnetic radiation is produced by:

1. Power lines.
2. All electric transport and its infrastructure.
3. Radio and television towers, as well as mobile and mobile communication stations.
4. Elevators and other lifting equipment using electromechanical power plants.
5. Network voltage conversion devices (waves emanating from a distribution substation or transformer).

Separately, there is special equipment that is used in medicine and emits hard radiation. Examples include MRI, X-ray machines and the like.

The influence of electromagnetic radiation on humans

In the course of numerous studies, scientists have come to the sad conclusion that long-term exposure to EMR contributes to a real explosion of diseases. However, many disorders occur at the genetic level. Therefore, protection against electromagnetic radiation is relevant. This is due to the fact that EMR has a high level of biological activity. In this case, the result of the influence depends on:

1. The nature of the radiation.
2. Duration and intensity of influence.

Specific moments of influence

It all depends on the localization. Absorption of radiation can be local or general. An example of the second case is the effect that power lines have. An example of local exposure is the electromagnetic waves emitted by a digital watch or mobile phone. Thermal effects should also be mentioned. Due to the vibration of molecules, the field energy is converted into heat. Microwave emitters operate on this principle and are used to heat various substances. It should be noted that when influencing a person, the thermal effect is always negative, and even harmful. It should be noted that we are constantly exposed to radiation. At work, at home, moving around the city. Over time, the negative effect only intensifies. Therefore, protection against electromagnetic radiation is becoming increasingly important.

How can you protect yourself?

Initially, you need to know what you are dealing with. A special device for measuring radiation will help with this. It will allow you to assess the security situation. In production, absorbent screens are used for protection. But, alas, they are not designed for use at home. To get started, here are three tips you can follow:

1. You should stay at a safe distance from devices. For power lines, television and radio towers, this is at least 25 meters. With CRT monitors and televisions, thirty centimeters is enough. Electronic watches should be no closer than 5 cm. And it is not recommended to bring radios and cell phones closer than 2.5 centimeters. You can select a location using a special device - a flux meter. The permissible dose of radiation recorded by it should not exceed 0.2 µT.
2. Try to reduce the time you have to be exposed to radiation.
3. You should always turn off electrical appliances when not in use. After all, even when inactive, they continue to emit EMR.

About the silent killer

And we will conclude the article with an important, although rather poorly known in wide circles, topic - radiation. Throughout his life, development and existence, man was irradiated by natural background. Natural radiation can be roughly divided into external and internal exposure. The first includes cosmic radiation, solar radiation, the influence of the earth's crust and air. Even the building materials from which houses and structures are created generate a certain background.

Radiation has a significant penetrating force, so stopping it is problematic. So, in order to completely isolate the rays, you need to hide behind a lead wall 80 centimeters thick. Internal radiation occurs when natural radioactive substances enter the body along with food, air, and water. Radon, thoron, uranium, thorium, rubidium, and radium can be found in the bowels of the earth. All of them are absorbed by plants, can be in water - and when eaten, they enter our body.

summary of other presentations

“Electrolysis of solutions and melts” - Michael Faraday (1791 – 1867). Do not allow electrolyte to splash. Process diagrams. Lesson objectives: Electrolytes are complex substances whose melts and solutions conduct electric current. GBOU secondary school No. 2046, Moscow. Cu2+ is an oxidizing agent. Salts, alkalis, acids. Safety rules when working on a PC. Safety regulations. The process of adding electrons by ions is called reduction. Cathode. Rock theme: “Electrolysis of melts and solutions of oxygen-free salts.

“Physics of the magnetic field” - By placing a steel rod inside the solenoid, we get the simplest electromagnet. Let's roughly count the number of magnetized nails. Consider the magnetic field of a conductor coiled in the form of a spiral. Field line method. Goals and objectives of the project: A magnetic needle is located near a straight wire. Magnetic field source.

“Atomic Energy” - At such congresses, issues related to installation work at nuclear power plants are resolved. Radioactive waste is generated at almost all stages of the nuclear cycle. To the North Of course, nuclear energy can be abandoned altogether. Nuclear power plants, thermal power plants, hydroelectric power plants are modern civilization. Zaporozhye NPP. Energy: “against”.

“Physics of Light” - Selection of glasses. Construction of an image in a diverging lens. Mirror telescope (reflector). Converging lens. Geometric optics. The straightness of light propagation explains the formation of shadows. A solar eclipse is explained by the linear propagation of light. Converging (a) and diverging (b) lenses. Human eye. Propagation of light in a fiber light guide.

“Electrical phenomena, grade 8” - Repel. Contact. Substances. The process of imparting an Electric charge to the body g. Friction. Electroscope electrometer. Devices. Electric charge. 8th grade. Electrical phenomena Municipal educational institution Pervomaiskaya secondary school Khairullina Galina Aleksandrovna. + TWO types of charges -. Electrical phenomena early 17th century. Non-conductors (Dielectrics) - ebonite - amber Porcelain rubber. From dielectrics. ELECTRON (Greek) - AMBER. Charges do not disappear or appear, but are only redistributed between two bodies. Insulators. They attract straws, fluff, and fur. Friction. Both bodies are electrified.

“Lomonosov's activities” - Training was conducted all year round. : Literary activity. Development of Lomonosov's activities. Lomonosov is 300 years old. A new period in life. Travel to Moscow. The importance of chemistry in Lomonosov's life.

Radiation is a physical process that results in the transfer of energy using electromagnetic waves. The reverse process of radiation is called absorption. Let us consider this issue in more detail, and also give examples of radiation in everyday life and nature.

Physics of radiation occurrence

Any body consists of atoms, which, in turn, are formed by nuclei, charged positively, and electrons, which form electron shells around the nuclei and are negatively charged. Atoms are designed in such a way that they can be in different energy states, that is, they can have both higher and lower energy. When an atom has the lowest energy, we speak of its ground state; any other energy state of the atom is called excited.

The existence of different energy states of an atom is due to the fact that its electrons can be located at certain energy levels. When an electron moves from a higher level to a lower one, the atom loses energy, which it emits into the surrounding space in the form of a photon, the carrier particle of electromagnetic waves. On the contrary, the transition of an electron from a lower to a higher level is accompanied by the absorption of a photon.

There are several ways to transfer an electron of an atom to a higher energy level, which involve the transfer of energy. This can be either the impact of external electromagnetic radiation on the atom in question, or the transfer of energy to it by mechanical or electrical means. In addition, atoms can receive and then release energy through chemical reactions.

Electromagnetic spectrum

Before moving on to examples of radiation in physics, it should be noted that each atom emits certain portions of energy. This happens because the states in which an electron can be in an atom are not arbitrary, but strictly defined. Accordingly, the transition between these states is accompanied by the emission of a certain amount of energy.

It is known from atomic physics that photons generated as a result of electronic transitions in an atom have energy that is directly proportional to their oscillation frequency and inversely proportional to the wavelength (a photon is an electromagnetic wave, which is characterized by propagation speed, length and frequency). Since an atom of a substance can only emit a certain set of energies, this means that the wavelengths of the emitted photons are also specific. The set of all these lengths is called the electromagnetic spectrum.

If the wavelength of a photon lies between 390 nm and 750 nm, then we speak of visible light, since a person can perceive it with his own eyes; if the wavelength is less than 390 nm, then such electromagnetic waves have high energy and are called ultraviolet, x-ray or gamma radiation. For lengths greater than 750 nm, photons have low energy and are called infrared, micro- or radio radiation.

Thermal radiation of bodies

Any body that has some temperature different from absolute zero emits energy, in this case we talk about thermal or temperature radiation. In this case, temperature determines both the electromagnetic spectrum of thermal radiation and the amount of energy emitted by the body. The higher the temperature, the more energy the body emits into the surrounding space, and the more its electromagnetic spectrum shifts to the high-frequency region. Thermal radiation processes are described by the Stefan-Boltzmann, Planck and Wien laws.

Examples of radiation in everyday life

As was said above, absolutely any body emits energy in the form of electromagnetic waves, but this process cannot always be seen with the naked eye, since the temperatures of the bodies around us are usually too low, so their spectrum lies in a low-frequency region invisible to humans.

A striking example of radiation in the visible range is an electric incandescent lamp. Passing along a spiral, the electric current heats the tungsten filament to 3000 K. Such a high temperature leads to the fact that the filament begins to emit electromagnetic waves, the maximum of which falls on the long-wavelength part of the visible spectrum.

Another example of radiation in everyday life is a microwave oven, which emits microwaves that are invisible to the human eye. These waves are absorbed by objects containing water, thereby increasing their kinetic energy and, as a result, temperature.

Finally, an example of radiation in the infrared range in everyday life is the radiator of a heating battery. We do not see its radiation, but we feel this warmth.

Natural emitting objects

Perhaps the most striking example of radiation in nature is our star - the Sun. The temperature on the surface of the Sun is about therefore its maximum radiation occurs at a wavelength of 475 nm, that is, it lies within the visible spectrum.

The sun heats up the planets around it and their satellites, which also begin to glow. Here it is necessary to distinguish between reflected light and thermal radiation. Thus, our Earth can be seen from space in the form of a blue ball precisely due to reflected sunlight. If we talk about the thermal radiation of the planet, then it also occurs, but lies in the region of the microwave spectrum (about 10 microns).

Besides reflected light, it is interesting to give another example of radiation in nature, which is associated with crickets. The visible light they emit has nothing to do with thermal radiation and is the result of a chemical reaction between atmospheric oxygen and luciferin (a substance found in insect cells). This phenomenon is called bioluminescence.