Interesting facts about physics. Physical phenomena are the world around us
Ticket No. 1
1. What does physics study? Some physical terms. Observations and experiments. Physical quantities. Measurement of physical quantities. Accuracy and error of measurements.
Physics is the science of the most general properties bodies and phenomena.
How does a person understand the world? How does he explore natural phenomena, obtaining scientific knowledge about him?
A person receives his very first knowledge from observations behind nature.
To obtain the correct knowledge, sometimes simple observation is not enough and you need to carry out experiment – specially prepared experiment .
Experiments are carried out by scientists a predetermined plan with a specific purpose .
During the experiments measurements are taken using special instruments of physical quantities. Examples physical quantities are: distance, volume, speed, temperature.
So, the source of physical knowledge is observations and experiments.
Physical laws are based and verified on facts established empirically. No less important way knowledge - theoretical description of the phenomenon . Physical theories make it possible to explain known phenomena and predict new, not yet discovered ones.
Changes that occur with bodies are called physical phenomena.
Physical phenomena are divided into several types.
Types of physical phenomena:
1. Mechanical phenomena (for example, the movement of cars, airplanes, celestial bodies, fluid flow).
2. Electrical phenomena (eg electricity, heating of current-carrying conductors, electrification of bodies).
3. Magnetic phenomena (for example, the effect of magnets on iron, the influence magnetic field Earth to the compass needle).
4. Optical phenomena (for example, reflection of light from mirrors, emission of light rays from various light sources).
5. Thermal phenomena (melting ice, boiling water, thermal expansion of bodies).
6. Atomic phenomena (for example, the operation of atomic reactors, nuclear decay, processes occurring inside stars).
7. Sound phenomena (bell ringing, music, thunder, noise).
Physical terms- these are special words that are used in physics for brevity, certainty and convenience.
Physical body– this is every object around us. (Showing physical bodies: pen, book, desk)
Substance- this is all that they are made of physical bodies. (Showing physical bodies consisting of different substances)
Matter- this is everything that exists in the Universe regardless of our consciousness (celestial bodies, plants, animals, etc.)
Physical phenomena- these are changes that occur with physical bodies.
Physical quantities- these are the measurable properties of bodies or phenomena.
Physical devices– these are special devices that are designed to measure physical quantities and conduct experiments.
Physical quantities:
height h, mass m, path s, speed v, time t, temperature t, volume V, etc.
Units of measurement of physical quantities:
International system SI units:
(international system)
Basic:
Length - 1 m - (meter)
Time - 1 s - (second)
Weight - 1 kg - (kilogram)
Derivatives:
Volume - 1 m³ - (cubic meter)
Speed - 1 m/s - (meter per second)
In this expression:
number 10 - numerical value of time,
the letter “s” is an abbreviation for a unit of time (second),
and the combination of 10 s is the time value.
Prefixes to unit names:
To make it more convenient to measure physical quantities, in addition to the basic units, multiple units are used, which are in 10, 100, 1000, etc. more basic
g - hecto (×100) k – kilo (× 1000) M – mega (× 1000 000)
1 km (kilometer) 1 kg (kilogram)
1 km = 1000 m = 10³ m 1 kg = 1000 g = 10³ g
1. Diffusion. We encounter this phenomenon in the kitchen all the time. Its name is derived from the Latin diffusio - interaction, dispersion, distribution. This is the process of mutual penetration of molecules or atoms of two adjacent substances. The rate of diffusion is proportional to the cross-sectional area of the body (volume), and the difference in concentrations and temperatures of the substances being mixed. If there is a temperature difference, then it determines the direction of propagation (gradient) - from hot to cold. As a result, spontaneous equalization of the concentrations of molecules or atoms occurs.
This phenomenon can be observed in the kitchen when odors spread. Thanks to the diffusion of gases, sitting in another room, you can understand what is being prepared. As you know, natural gas is odorless, and an additive is added to it to make it easier to detect domestic gas leaks. Cutting bad smell adds an odorant such as ethyl mercaptan. If the burner does not light up the first time, then we can smell a specific smell, which we have known since childhood as the smell of household gas.
And if you throw grains of tea or a tea bag into boiling water and don’t stir, you can see how the tea infusion in volume clean water. This is the diffusion of liquids. An example of diffusion in a solid would be the pickling of tomatoes, cucumbers, mushrooms or cabbage. Salt crystals in water disintegrate into Na and Cl ions, which, moving chaotically, penetrate between the molecules of substances in vegetables or mushrooms.
2. Change of state of aggregation. Few of us have noticed that in a glass of water left, after a few days, the same part of the water evaporates at room temperature as when boiled for 1-2 minutes. And when we freeze food or water for ice cubes in the refrigerator, we don’t think about how this happens. Meanwhile, these most ordinary and frequent kitchen phenomena are easily explained. A liquid has an intermediate state between solids and gases. At temperatures other than boiling or freezing, the attractive forces between molecules in a liquid are not as strong or weak as in solids and gases. Therefore, for example, only receiving energy (from sun rays, air molecules at room temperature), liquid molecules from the open surface gradually pass into the gas phase, creating vapor pressure above the liquid surface. The rate of evaporation increases with increasing surface area of the liquid, increasing temperature, and decreasing external pressure. If the temperature is increased, the vapor pressure of this liquid reaches external pressure. The temperature at which this occurs is called the boiling point. The boiling point decreases as the external pressure decreases. Therefore in mountainous area water boils faster.
Conversely, when the temperature drops, water molecules lose kinetic energy to the level of attractive forces between themselves. They no longer move chaotically, which allows the formation of a crystal lattice like solids. The temperature of 0 °C at which this occurs is called the freezing point of water. When water freezes, it expands. Many may have become familiar with this phenomenon when they placed a plastic bottle with a drink in the freezer for quick cooling and forgot about it, and then the bottle burst. When cooled to a temperature of 4 °C, there is first an increase in the density of water, at which its maximum density and minimum volume are achieved. Then, at temperatures from 4 to 0 °C, the bonds in the water molecule are rearranged, and its structure becomes less dense. At a temperature of 0 °C, the liquid phase of water changes to the solid phase. After water completely freezes and turns into ice, its volume increases by 8.4%, which leads to expansion plastic bottle. The liquid content of many products is low, so they do not increase in volume as much when frozen.
3. Absorption and adsorption. These two almost inseparable phenomena, named from the Latin sorbeo (to absorb), are observed, for example, when heating water in a kettle or pan. A gas that has no chemical effect on a liquid can nevertheless be absorbed by it upon contact with it. This phenomenon is called absorption. When gases are absorbed by solid fine-grained or porous bodies, most of them accumulate tightly and are retained on the surface of the pores or grains and are not distributed throughout the entire volume. In this case, the process is called adsorption. These phenomena can be observed when boiling water - bubbles separate from the walls of a pan or kettle when heated. The air released from water contains 63% nitrogen and 36% oxygen. But in general atmospheric air contains 78% nitrogen and 21% oxygen.
Salt in an unclosed container it can become damp due to its hygroscopic properties - the absorption of water vapor from the air. And soda acts as an adsorbent when it is placed in the refrigerator to remove odors.
4. Manifestation of Archimedes' law. Once we're ready to cook the chicken, we fill the pot about halfway or ¾ full with water depending on the size of the chicken. When immersing the carcass in a pan of water, we notice that the weight of the chicken in the water noticeably decreases, and the water rises to the edges of the pan.
This phenomenon is explained by buoyant force or Archimedes' law. In this case, a body immersed in a liquid is subject to a buoyancy force equal to the weight of the liquid in the volume of the immersed part of the body. This force is called the Archimedes force, as is the law itself that explains this phenomenon.
5. Surface tension. Many people remember experiments with films of liquids, which were shown in physics lessons at school. A small wire frame with one movable side was dipped into soapy water and then pulled out. Surface tension forces in the film formed around the perimeter lifted the lower movable part of the frame. To keep it motionless, a weight was hung from it when the experiment was repeated. This phenomenon can be observed in a colander - after use, water remains in the holes in the bottom of this kitchen utensil. The same phenomenon can be observed after washing forks - on inner surface There are also streaks of water between some of the teeth.
The physics of liquids explains this phenomenon as follows: the molecules of a liquid are so close to each other that the attractive forces between them create surface tension in the plane of the free surface. If the force of attraction of the water molecules of the liquid film is weaker than the force of attraction to the surface of the colander, then the water film breaks. Surface tension forces are also noticeable when we pour cereal or peas, beans, or add round grains of pepper into a pan of water. Some grains will remain on the surface of the water, while most will sink to the bottom under the weight of the rest. If you lightly press the floating grains with your fingertip or spoon, they will overcome the surface tension of the water and sink to the bottom.
6. Wetting and spreading. On a kitchen stove with a grease film, spilled liquid can form small spots, and on the table - one puddle. The thing is that in the first case, liquid molecules are more strongly attracted to each other than to the surface of the plate, where there is a fatty film not wetted by water, and on a clean table, the attraction of water molecules to the molecules of the table surface is higher than the attraction of water molecules among themselves. As a result, the puddle spreads out.
This phenomenon also relates to fluid physics and is related to surface tension. As you know, a soap bubble or liquid drops have a spherical shape due to surface tension forces. In a drop, liquid molecules are attracted to each other more strongly than to gas molecules, and tend to move inside the liquid drop, reducing its surface area. But, if there is a solid wetted surface, then part of the drop upon contact is stretched along it, because the molecules of the solid attract the molecules of the liquid, and this force exceeds the force of attraction between the molecules of the liquid. The degree of wetting and spreading over a solid surface will depend on which force is greater - the force of attraction between liquid molecules and solid molecules between themselves or the force of attraction of molecules inside the liquid.
This physical phenomenon has been widely used in industry since 1938, in the production of household goods, when the Teflon (polytetrafluoroethylene) material was synthesized in the DuPont laboratory. Its properties are used not only in the manufacture of cookware with non-stick coatings, but also in the production of waterproof, water-repellent fabrics and coatings for clothing and shoes. Teflon is noted in the Guinness Book of Records as the most slippery substance in the world. It has very low surface tension and adhesion (sticking), and is not wetted by water, fats, or many organic solvents.
7. Thermal conductivity. One of the most common phenomena in the kitchen that we can observe is the heating of a kettle or water in a pan. Thermal conduction is the transfer of heat through the movement of particles when there is a difference (gradient) in temperature. Among the types of heat conduction there is also convection. In the case of identical substances, liquids have less thermal conductivity than solids and more than gases. The thermal conductivity of gases and metals increases with increasing temperature, and that of liquids decreases. We encounter convection all the time, whether we stir soup or tea with a spoon, or open a window, or turn on the ventilation to ventilate the kitchen. Convection - from the Latin convectiō (transfer) - a type of heat exchange when the internal energy of a gas or liquid is transferred by jets and flows. There are natural and forced convection. In the first case, layers of liquid or air mix themselves when heated or cooled. And in the second case, mechanical mixing of the liquid or gas occurs - with a spoon, fan or other method.
8. Electromagnetic radiation. A microwave oven is sometimes called an ultra-high frequency oven, or microwave oven. The main element of every microwave is a magnetron, which converts electrical energy into microwave energy. electromagnetic radiation up to 2.45 gigahertz (GHz). The radiation heats the food by interacting with its molecules. Products contain dipole molecules containing positive and negative electrical charges on their opposite parts. These are molecules of fats, sugar, but most of all dipole molecules are in water, which is found in almost any product. The microwave field, constantly changing its direction, causes the molecules that line up along the power lines so that all the positively charged parts of the molecules “look”, now in one direction, then in the other. Molecular friction occurs and energy is released, which heats the food.
9. Induction. In the kitchen you can increasingly find induction cookers, the basis of which is this phenomenon. English physicist Michael Faraday discovered electromagnetic induction in 1831 and since then it is impossible to imagine our life without her. Faraday discovered the occurrence of an electric current in a closed circuit due to a change in the magnetic flux passing through this circuit. There is a well-known school experience when a flat magnet moves inside a spiral-shaped wire circuit (solenoid), and an electric current appears in it. There is also a reverse process - an alternating electric current in a solenoid (coil) creates an alternating magnetic field.
A modern induction cooker works on the same principle. Under the glass-ceramic heating panel (neutral to electromagnetic vibrations) such a plate contains an induction coil through which an electric current flows with a frequency of 20−60 kHz, creating an alternating magnetic field that induces eddy currents in a thin layer (skin layer) of the bottom of the metal cookware. Because of electrical resistance The cookware is heating up. These currents are no more dangerous than hot cookware on conventional stoves. The cookware must be steel or cast iron with ferromagnetic properties (attract a magnet).
10. Refraction of light. The angle of incidence of light is equal to the angle of reflection, and the propagation of natural light or light from lamps is explained by the dual, particle-wave nature: on the one hand, it electromagnetic waves, and on the other hand, photon particles that move at the highest speed possible in the Universe. In the kitchen you can observe such an optical phenomenon as the refraction of light. For example, when there is a transparent vase of flowers on the kitchen table, the stems in the water seem to shift at the boundary of the water surface relative to their continuation outside the liquid. The fact is that water, like a lens, refracts the rays of light reflected from the stems in the vase. A similar thing can be seen in a transparent glass of tea with a spoon in it. You can also see a distorted and enlarged image of beans or cereals at the bottom of a deep pan of clear water.
The natural world around us is simply teeming with various secrets and mysteries. Scientists have been looking for answers for centuries and sometimes trying to explain, but even the best minds of mankind still defy some amazing natural phenomena.
Sometimes you get the impression that strange flashes in the sky and spontaneously moving stones do not mean anything special. But, delving into the mysterious manifestations observed on our planet, you understand that it is impossible to answer many questions. Nature carefully hides its secrets, and people put forward new hypotheses, trying to unravel them.
Today we will look at physical phenomena in living nature that will make you take a fresh look at the world.
Physical phenomena
Each body consists of certain substances, but note that various actions affect the same bodies differently. For example, if you tear paper in half, the paper will still be paper. But if you set it on fire, all that will remain is ashes.
When the size, shape, state changes, but the substance remains the same and does not transform into another, such phenomena are called physical. They may be different.
Natural phenomena, examples of which we can observe in ordinary life, there are:
- Mechanical. The movement of clouds across the sky, the flight of an airplane, the fall of an apple.
- Thermal. Caused by temperature changes. During this process, the characteristics of the body change. If you heat ice, it becomes water, which transforms into steam.
- Electrical. Surely at quick removal Have you ever heard a specific crackling sound from your woolen clothes, similar to an electric discharge? And if you do all this in a dark room, you can still observe the sparks. Objects that, after friction, begin to attract lighter bodies are called electrified. Northern lights, lightning during a thunderstorm - vivid examples
- Light. Bodies that emit light are called. This includes the Sun, lamps and even representatives of the animal world: some types of deep-sea fish and fireflies.
Physical natural phenomena, examples of which we discussed above, are successfully used by people in Everyday life. But there are also those that to this day excite the minds of scientists and evoke universal admiration.
Northern lights
Perhaps this rightfully bears the status of the most romantic. High in the sky, colorful rivers form, covering an endless number of bright stars.
If you want to enjoy this beauty, the best place to do it is in the northern part of Finland (Lapland). There was a belief that the cause of its occurrence was the anger of the supreme gods. But the most popular legend of the Sami people was about a fabulous fox who hit the snow-covered plains with his tail, causing colored sparks to soar into the heights and illuminate the night sky.
Clouds in the form of pipes
Such a natural phenomenon can drag anyone into a state of relaxation, inspiration, and illusion for a long time. Such sensations are created due to the shape of large pipes that change their color.
You can see it in those places where a thunderstorm front begins to form. This natural phenomenon is most often observed in countries with a tropical climate.
Stones that move in Death Valley
There are various natural phenomena, examples of which are quite understandable with scientific point vision. But there are those that defy human logic. One of the mysteries of nature is considered to be. This phenomenon can be observed in the American national park called Death Valley. Many scientists are trying to explain the movement strong winds, which are often found in desert areas, and the presence of ice, since it was in winter that the movement of stones became more intense.
During the research, scientists made observations of 30 stones, the weight of which was no more than 25 kg. Over seven years, 28 out of 30 stone blocks moved 200 meters from the starting point.
Whatever the scientists’ guesses, they do not have a clear answer regarding this phenomenon.
Ball lightning
Appearing after or during a thunderstorm is called ball lightning. There is an assumption that Nikola Tesla managed to create ball lightning in his laboratory. He wrote that he had not seen anything like this in nature (we were talking about fireballs), but he figured out how they form and even managed to recreate this phenomenon.
Modern scientists have not been able to achieve similar results. And some even question the existence of this phenomenon as such.
We have considered only some natural phenomena, examples of which show how amazing and mysterious our surrounding world is. How many unknown and interesting things we still have to learn in the process of developing and improving science. How many discoveries await us ahead?
As a rule, few students like school science about the properties and structure of matter. And indeed - tedious problem solving, complex formulas, incomprehensible combinations of special characters, etc. In general, sheer gloom and melancholy. If you think so, then this material is definitely for you.
In this article we will tell you the most interesting facts about physics, which will make even an indifferent person take a look at natural science differently. Without a doubt, physics is very useful and interesting science, and related to it interesting facts about the Universe - mass.
1. Why is the sun red in the morning and evening? A wonderful example of a fact from physical phenomena in nature. Actually, the light of a hot celestial body is white. White glow, with its spectral change, tends to acquire all the colors of the rainbow.
In the mornings and evenings, the sun's rays pass through numerous layers of the atmosphere. Air molecules and tiny dry dust particles can block the passage of sunlight, best allowing only red rays to pass through.
2. Why does time tend to stop at the speed of light? According to the general theory of relativity proposed by absolute value the speed of propagation of electromagnetic waves in a vacuum environment is constant and equal to three hundred million meters per second. This is actually a unique phenomenon, given that nothing in our universe can exceed the speed of light, but this is still a theoretical opinion.
In one of the theories, authored by Einstein, there is an interesting section that says that the more you gain speed, the slower time begins to move in comparison with surrounding objects. For example, if you drive a car for an hour, you will age slightly less than if you just lay on your bed at home watching television. Nanoseconds are unlikely to have a noticeable impact on your life, but the proven fact remains a fact.
3. Why doesn’t a bird sitting on an electric wire die from electric shock? A bird sitting on a power line is not shocked because its body is not conductive enough. In places where the bird comes into contact with the wire, a so-called parallel connection is created, and since high-voltage wire is the best conductor of current; only a minimum current flows through the body of the bird itself, which is not able to cause significant harm to the health of the bird.
But as soon as a feathered and downy vertebrate animal standing on a wire comes into contact with a grounded object, for example, a metal part of a high-voltage power line, it instantly burns out, because the resistance in this case becomes too great, and the entire electric current pierces the body of the unfortunate bird.
4. How much dark matter is there in the Universe? We live in a material world, and all that we can see around us is matter. We have the opportunity to touch it, sell it, buy it, we can dispose of the material at our discretion. However, in the Universe there is not only objective reality in the form of matter, but also dark matter (physicists often call it “dark horse”) - this is a type of matter that does not tend to emit electromagnetic waves and interact with them.
For obvious reasons, no one was able to see or touch dark matter. Scientists have come to the conclusion that it is present in the Universe, having repeatedly observed indirect evidence of its existence. It is generally accepted that its share in the composition of the Universe occupies 22%, while matter familiar to us occupies only 5%.
5. Are there Earth-like planets in the Universe? Undoubtedly they exist! Taking into account the scale of the Universe, the probability of this is estimated by scientists to be quite high.
However, only recently scientists from NASA began to actively discover such planets located no further than 50 light years from the Sun, called exoplanets. Exoplanets are Earth-like planets that orbit the axis of other stars. To date, more than 3,500 Earth-like planets have been found, and scientists are increasingly discovering alternative places for people to live.
6. All objects fall at the same speed. It may seem to some that heavy objects fall down much faster than light objects - this is a completely logical assumption. Surely a hockey puck falls at a much higher speed than a bird feather. In fact, this is so, but not due to the fault of universal gravity - the main reason why we can observe this is that the gas shell surrounding the planet provides powerful resistance.
400 years have passed since I first realized that universal gravity applies to all objects equally, regardless of their gravity. If you could repeat the experiment with a hockey puck and a bird feather in space (where there is no Atmosphere pressure), they would fall down at the same speed.
7. How do the northern lights appear on Earth? Throughout their existence, people have observed one of the natural wonders of our planet - the northern lights, but at the same time they could not understand what it is and where it comes from. Ancient people, for example, had their own idea: a group of indigenous Eskimo peoples believed that this was a sacred light that was emitted by the souls of deceased people, and in the ancients European countries assumed that it was fighting, which the defenders of their state who died in wars are forever doomed to lead.
The first scientists came to the solution mysterious phenomenon a little closer - they put forward for worldwide discussion the theory that the glow arises as a result of the reflection of light rays from ice blocks. Modern researchers believe that the multi-colored light is caused by the collision of millions of atoms and dust particles from our atmospheric shell. The fact that the phenomenon is widespread mainly at the poles is explained by the fact that in these areas the power of the Earth's magnetic field is especially strong.
8. Quicksand sucking deep. The force of pulling a stuck foot out of the sand, supersaturated with air and moisture from rising sources, at a speed of 0.1 m/s is equal to the force of lifting an average passenger car. A remarkable fact: quicksand is a non-Newtonian fluid that is not able to completely absorb the human body.
Therefore, those who are mired in quicksand people die from exhaustion or dehydration, excessive ultraviolet irradiation or for other reasons. God forbid, you find yourself in such a situation; it is worth remembering that it is strictly forbidden to make sudden movements. Try to tilt your body back as high as possible, spread your arms wide and wait for the rescue team to help.
9. Why is the unit of measurement for the strength of alcoholic drinks and temperature called the same - degree? In the 17th-18th centuries, the generally accepted scientific principle of caloric was in effect - the so-called weightless matter, which was located in physical bodies and was the cause of thermal phenomena.
According to this principle, more heated physical bodies contain many times more concentrated caloric than less heated ones, therefore the strength of alcoholic beverages was determined as the temperature of the mixture of substance and caloric.
10. Why doesn't a drop of rain kill a mosquito? Physicists have managed to figure out how mosquitoes manage to fly in rainy weather and why raindrops do not kill bloodsuckers. The insects are the same size as a raindrop, but one droplet weighs 50 times more than a mosquito. The impact of a drop can be compared to a car or even a bus crashing into a person’s body.
Despite this, the rain does not disturb the insects. The question arises - why? The flight speed of a raindrop is about 9 meters per second. When an insect gets inside the shell of a drop, enormous pressure is applied to it. For example, if a person were subjected to such pressure, his body would not be able to withstand it, but a mosquito is able to safely withstand such stress due to the specific structure of the skeleton. And in order to continue flying in a given direction, the mosquito simply needs to shake off its hairs from a drop of rain.
Scientists say that the volume of the drop is quite enough to kill a mosquito if it is on the ground. And the absence of consequences after a drop of rain hits a mosquito is attributed to the fact that the movement associated with the drop allows one to minimize the transfer of energy to the insect.
There is still an unlimited number of facts in this science. And if today’s famous scientists were not interested in physics, we would not know all the interesting things that are happening around us. The achievements of famous physicists allowed us to understand the importance of substantiating laws-prohibitions, laws-statements and absolute laws for the life of mankind.
Man lives in the natural world. You yourself and everything that surrounds you - the air, trees, river, sun - are different natural objects. Changes constantly occur with natural objects, which are called natural phenomena.
Since ancient times, people have tried to understand: how and why various phenomena occur? How do birds fly and why don't they fall? How can a tree float on water and why does it not sink? Some natural phenomena are thunder and lightning, solar and lunar eclipse- scared people until scientists figured out how and why they arise.
By observing and studying phenomena occurring in nature, people have found application for them in their lives. Observing the flight of birds (Fig. 1), people designed an airplane (Fig. 2).
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| Rice. 1 | Rice. 2 |
Watching a floating tree, man learned to build ships and conquered the seas and oceans. Having studied the method of movement of the jellyfish (Fig. 3), scientists came up with a rocket engine (Fig. 4). By observing lightning, scientists discovered electricity, without which people today cannot live and work. All kinds of household electrical devices (lighting lamps, televisions, vacuum cleaners) surround us everywhere. Various power tools (electric drill, power saw, sewing machine) are used in school workshops and in production.
Scientists divided all physical phenomena into groups (Fig. 6):
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| Rice. 6 |
Mechanical phenomena- these are phenomena that occur with physical bodies when they move relative to each other (the revolution of the Earth around the Sun, the movement of cars, the swing of a pendulum).
Electrical phenomena- these are phenomena that arise during the appearance, existence, movement and interaction of electrical charges (electric current, lightning).
Magnetic phenomena- these are phenomena associated with the emergence of magnetic properties in physical bodies (attraction of iron objects by a magnet, turning the compass needle to the north).
Optical phenomena- these are phenomena that arise during the propagation, refraction and reflection of light (reflection of light from a mirror, mirages, the appearance of shadows).
Thermal phenomena- these are phenomena associated with heating and cooling of physical bodies (boiling a kettle, the formation of fog, the transformation of water into ice).
Atomic phenomena are phenomena that occur when there is a change internal structure substances of physical bodies (glow of the Sun and stars, atomic explosion).
Observe and explain. 1. Give an example of a natural phenomenon. 2. To which group of physical phenomena does it belong? Why? 3. Name the physical bodies that participated in physical phenomena.