We often take for granted everything that happens to us on earth, but every minute our lives are controlled by many forces. There are a surprising number of unusual, paradoxical, or challenging physical laws that we encounter every day. In a fun exploration of physics everyone should know, we talk about common occurrences that many people consider a mystery, strange forces we can't understand, and how science fiction can become reality through light manipulation.
10. Cold wind effect
Our perception of temperature is quite subjective. Humidity, individual physiology, and even our mood can change our perception of hot and cold temperatures. The same thing happens with the wind: the temperature we feel is not real. The air that directly surrounds the human body serves as a kind of air cloak. This insulating air cushion keeps you warm. When the wind blows on you, this air cushion is blown away and you begin to feel the real temperature, which is much colder. The cool wind effect only affects those objects that produce heat.
9. The faster you go, the stronger the impact.
People tend to think linearly, mostly based on observational principles; if one raindrop weighs 50 milligrams, two raindrops should weigh about 100 milligrams. However, the forces that control the universe often show us a different result due to the distribution of forces. An object moving at 40 kilometers per hour will hit a wall with a certain force. If you double the speed of an object to 80 kilometers per hour, impact force will increase not two, but four times. This law explains why accidents on highways are much more destructive than accidents in cities.
8. Orbit is just a constant free fall.
Satellites emerge as a notable recent application to stars, but we rarely think about the concept of "orbit." We know in general that objects move around planets or large celestial bodies and never fall. But the reason for the appearance of orbits is surprisingly paradoxical. If you drop an object, it falls to the surface. However, if it is high enough and moving at a fast enough speed, it will swing away from the ground in an arc. The same effect prevents the earth from colliding with the sun.
7. Heat causes freezing.
Water is the most important liquid on the ground. This is the most mysterious and paradoxical connection in nature. One of the little-known properties of water is, for example, that warm water freezes faster than cold water. It is not yet fully understood how this happens, but this phenomenon, known as the Mpemba paradox, was discovered by Aristotle about 3,000 years ago. But why exactly this happens remains a mystery.
6. Air pressure.
IN this moment you are exposed to air pressure equal to approximately 1000 kilograms, the same as a small car weighs. This is due to the fact that the atmosphere itself is quite heavy, and a person located at the bottom of the ocean experiences a pressure of 2.3 kg per square centimeter. Our body can withstand such pressure, and it cannot crush us. However, sealed objects, such as plastic bottles, thrown from very high altitudes return to the ground in a compressed state.
5. Metallic hydrogen.
Hydrogen is the first element in the periodic table, making it the simplest element in the Universe. Its atomic number 1 means it has 1 proton, 1 electron and no neutrons. Although hydrogen is known as a gas, it can exhibit some properties that are more common to metals than to gases. Hydrogen is located in periodic table just above sodium, a volatile metal that is part of the composition of table salt. Physicists have long realized that hydrogen behaves like a high-pressure metal, like that found on stars and at the core of gas giant planets. Trying to make such a compound on earth requires a lot of effort, but some scientists believe they have already created small samples by applying pressure to diamond crystals.
4. Coriolis effect.
Thanks pretty large size planet, a person does not feel its movement. However, the clockwise motion of the Earth causes objects traveling in the northern hemisphere to move slightly clockwise as well. This phenomenon is known as the Coriolis effect. Since the Earth's surface moves at a certain speed relative to the atmosphere, the difference between the rotation of the Earth and the movement of the atmosphere causes an object moving north to pick up the energy of the Earth's rotation and begin to veer east. The opposite phenomenon is observed in the southern hemisphere. As a result, navigation systems must take into account the Coriolis force to avoid heading off course.
3. Doppler effect.
Sound may be an independent phenomenon, but the perception of sound waves depends on speed. Austrian physicist Christian Doppler discovered that when a moving object, such as a siren, emits sound waves, they accumulate in front of the object and dissipate behind it. This phenomenon, known as the Doppler effect, causes the sound of an approaching object to become a pitch higher due to the shortening of the sound wavelengths. After the object passes by, the trailing sound waves lengthen and, accordingly, become tones lower.
2. Evaporation.
It would be logical to assume that chemicals must pass through a liquid state in the process of transitioning from a solid to a gaseous state. However, water is capable of immediately transforming from a solid to a gas under certain circumstances. Sublimation, or evaporation, can cause glaciers to disappear when the sun turns the ice into steam. In the same way, metals, such as arsenic, can turn into a gas when heated, releasing toxic gases. Water can evaporate below its melting point when exposed to a heat source.
1. Disguised devices.
Rapidly evolving technology is transforming stories science fiction V scientific facts. We can see objects when light of different wavelengths is reflected from them. Scientists have theorized that objects can be considered invisible when exposed to certain light. If the light around an object can be scattered, it becomes invisible to human eye. IN Lately this theory became a reality when scientists invented a transparent hexagonal prism that scattered light around an object placed inside. When placed in an aquarium, the prism made goldfish, which floated there, invisible, and on the ground the livestock disappeared from sight. This cloaking effect works on the same principles as aircraft that cannot be detected by radar.
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About the world around us. In addition to ordinary curiosity, this was caused by practical needs. After all, for example, if you know how to lift
and move heavy stones, you will be able to build strong walls and build a house in which it is more convenient to live than in a cave or dugout. And if you learn to smelt metals from ores and make plows, scythes, axes, weapons, etc., you will be able to plow the field better and get a higher harvest, and in case of danger you will be able to protect your land.
In ancient times, there was only one science - it united all the knowledge about nature that humanity had accumulated by that time. Nowadays this science is called natural science.
Learning about physical science
Another example of an electromagnetic field is light. You will become familiar with some of the properties of light in Section 3.
3. Remembering physical phenomena
The matter around us is constantly changing. Some bodies move relative to each other, some of them collide and, possibly, collapse, others are formed from some bodies... The list of such changes can be continued and continued - it is not without reason that in ancient times the philosopher Heraclitus remarked: “Everything flows, everything changes.” Scientists call changes in the world around us, that is, in nature, a special term - phenomena.
Rice. 1.5. Examples of natural phenomena
Rice. 1.6. A complex natural phenomenon - a thunderstorm can be represented as a combination of a number of physical phenomena
Sunrise and sunset, gathering snow avalanche, a volcanic eruption, a horse running, a panther jumping - all these are examples of natural phenomena (Fig. 1.5).
To better understand complex natural phenomena, scientists divide them into a collection of physical phenomena - phenomena that can be described using physical laws.
In Fig. Figure 1.6 shows a set of physical phenomena that form a complex natural phenomenon - a thunderstorm. Thus, lightning - a huge electrical discharge - is an electromagnetic phenomenon. If lightning strikes a tree, it will flare up and begin to release heat - physicists in this case talk about a thermal phenomenon. The rumble of thunder and the crackle of flaming wood are sound phenomena.
Examples of some physical phenomena are given in the table. Take a look at the first row of the table, for example. What can be common between the flight of a rocket, the fall of a stone and the rotation of an entire planet? The answer is simple. All examples of phenomena given in this line are described by the same laws - the laws of mechanical motion. Using these laws, we can calculate the coordinates of any moving body (be it a stone, a rocket or a planet) at any point in time that interests us.
Rice. 1.7 Examples of electromagnetic phenomena
Each of you, taking off a sweater or combing your hair with a plastic comb, probably paid attention to the tiny sparks that appeared. Both these sparks and the mighty discharge of lightning belong to the same electromagnetic phenomena and, accordingly, are subject to the same laws. Therefore, you should not wait for a thunderstorm to study electromagnetic phenomena. It is enough to study how safe sparks behave to understand what to expect from lightning and how to avoid possible danger. For the first time such research was carried out by the American scientist B. Franklin (1706-1790), who invented an effective means of protection against lightning discharges - a lightning rod.
Having studied physical phenomena separately, scientists establish their relationship. Thus, a lightning discharge (an electromagnetic phenomenon) is necessarily accompanied by a significant increase in temperature in the lightning channel (a thermal phenomenon). The study of these phenomena in their interrelation made it possible not only to better understand the natural phenomenon of a thunderstorm, but also to find a way for the practical application of electromagnetic and thermal phenomena. Surely each of you, passing by a construction site, saw workers in protective masks and blinding flashes of electric welding. Electric welding (a method of joining metal parts using an electric discharge) is an example of the practical use of scientific research.
4. Determine what physics studies
Now that you have learned what matter and physical phenomena are, it is time to determine what the subject of physics is. This science studies: the structure and properties of matter; physical phenomena and their relationships.
- let's sum it up
The world around us consists of matter. There are two types of matter: the substance from which all physical bodies are made, and the field.
Changes are constantly taking place in the world that surrounds us. These changes are called phenomena. Thermal, light, mechanical, sound, electromagnetic phenomena are all examples of physical phenomena.
The subject of physics is the structure and properties of matter, physical phenomena and their relationships.
- Control questions
What does physics study? Give examples of physical phenomena. Can events that occur in a dream or imagination be considered physical phenomena? 4. What substances do the following bodies consist of: a textbook, a pencil, a soccer ball, a glass, a car? What physical bodies can consist of glass, metal, wood, plastic?
Physics. 7th grade: Textbook / F. Ya. Bozhinova, N. M. Kiryukhin, E. A. Kiryukhina. - X.: Publishing house "Ranok", 2007. - 192 p.: ill.
Lesson content lesson notes and supporting frame lesson presentation interactive technologies accelerator teaching methods Practice tests, testing online tasks and exercises homework workshops and trainings questions for class discussions Illustrations video and audio materials photographs, pictures, graphs, tables, diagrams, comics, parables, sayings, crosswords, anecdotes, jokes, quotes Add-onsIn 1979, the Gorky People's University of Scientific and Technical Creativity released methodological materials for its new development, “A comprehensive method for searching for new technical solutions.” We plan to introduce site readers to this interesting development, which in many ways was significantly ahead of its time. But today we invite you to familiarize yourself with a fragment of the third part teaching materials, published under the title "Arrays of Information". The list of physical effects proposed in it includes only 127 items. Now specialized computer programs offer more detailed versions of physical effects indexes, but for a user who is still “not covered” by software support, the table of applications of physical effects created in Gorky is of interest. Its practical benefit is that at the input the solver had to indicate which function from those listed in the table it wants to provide and which type of energy it plans to use (as they would say now, indicate resources). The numbers in the cells of the table are the numbers of physical effects in the list. Each physical effect is provided with references to literary sources (unfortunately, almost all of them are currently bibliographic rarities).
The work was carried out by a team that included teachers from Gorky People's University: M.I. Vainerman, B.I. Goldovsky, V.P. Gorbunov, L.A. Zapolyansky, V.T. Korelov, V.G. Kryazhev, A.V. Mikhailov, A.P. Sokhin, Yu.N. Shelomok. The material presented to the reader’s attention is compact, and therefore can be used as handouts in classes at public schools of technical creativity.
Editor
List of physical effects and phenomena
Gorky People's University of Scientific and Technical Creativity
Gorky, 1979
| N | Name of physical effect or phenomenon | Short description essence of a physical effect or phenomenon | Typical functions (actions) performed (see Table 1) | Literature |
| 1 | 2 | 3 | 4 | 5 |
| 1 | Inertia | The movement of bodies after the cessation of forces. A rotating or translational body moving by inertia can accumulate mechanical energy and produce a force effect | 5, 6, 7, 8, 9, 11, 13, 14, 15, 21 | 42, 82, 144 |
| 2 | Gravity | force interaction of masses at a distance, as a result of which bodies can move, approaching each other | 5, 6, 7, 8, 9, 11, 13, 14, 15 | 127, 128, 144 |
| 3 | Gyroscopic effect | Bodies rotating at high speed are able to maintain the position of their axis of rotation unchanged. External force to change the direction of the rotation axis leads to precession of the gyroscope, proportional to the force | 10, 14 | 96, 106 |
| 4 | Friction | The force arising from the relative movement of two contacting bodies in the plane of their contact. Overcoming this force leads to the release of heat, light, wear and tear | 2, 5, 6, 7, 9, 19, 20 | 31, 114, 47, 6, 75, 144 |
| 5 | Replacing static friction with motion friction | When the rubbing surfaces vibrate, the friction force decreases | 12 | 144 |
| 6 | Wear-free effect (Kragelsky and Garkunov) | The steel-bronze pair with glycerin lubricant practically does not wear out | 12 | 75 |
| 7 | Johnson-Rabek effect | Heating the metal-semiconductor rubbing surfaces increases the friction force | 2, 20 | 144 |
| 8 | Deformation | Reversible or irreversible (elastic or plastic deformation) change in the relative position of body points under the influence of mechanical forces, electric, magnetic, gravitational and thermal fields, accompanied by the release of heat, sound, light | 4, 13, 18, 22 | 11, 129 |
| 9 | Poynting effect | Elastic elongation and increase in volume of steel and copper wires when twisted. The properties of the material do not change | 11, 18 | 132 |
| 10 | Relationship between strain and electrical conductivity | When a metal transitions to a superconducting state, its plasticity increases | 22 | 65, 66 |
| 11 | Electroplastic effect | Increasing ductility and reducing brittleness of metal under the influence of high-density direct electric current or pulsed current | 22 | 119 |
| 12 | Bauschinger effect | Reduction of resistance to initial plastic deformations when the sign of the load changes | 22 | 102 |
| 13 | Alexandrov effect | With increasing ratio of the masses of elastically colliding bodies, the energy transfer coefficient increases only to a critical value, determined by the properties and configuration of the bodies | 15 | 2 |
| 14 | Memory alloys | Parts made of some alloys (titanium-nickel, etc.) deformed by mechanical forces after heating restore exactly their original shape and are capable of creating significant force impacts. | 1, 4, 11, 14, 18, 22 | 74 |
| 15 | Explosion phenomenon | Ignition of substances due to their instant chemical decomposition and the formation of highly heated gases, accompanied by a strong sound, the release of significant energy (mechanical, thermal), and a flash of light | 2, 4, 11, 13, 15, 18, 22 | 129 |
| 16 | Thermal expansion | Changes in the size of bodies under the influence of a thermal field (during heating and cooling). May be accompanied by significant effort | 5, 10, 11, 18 | 128,144 |
| 17 | First-order phase transitions | A change in the density of the aggregate state of substances at a certain temperature, accompanied by release or absorption | 1, 2, 3, 9, 11, 14, 22 | 129, 144, 33 |
| 18 | Phase transitions of the second order | Abrupt change in heat capacity, thermal conductivity, magnetic properties, fluidity (superfluidity), plasticity (superplasticity), electrical conductivity (superconductivity) upon reaching a certain temperature and without energy exchange | 1, 3, 22 | 33, 129, 144 |
| 19 | Capillarity | Spontaneous flow of liquid under the action of capillary forces in capillaries and half-open channels (microcracks and scratches) | 6, 9 | 122, 94, 144, 129, 82 |
| 20 | Laminarity and turbulence | Laminarity is the ordered movement of a viscous liquid (or gas) without interlayer mixing with a flow rate decreasing from the center of the pipe to the walls. Turbulence is the chaotic movement of a liquid (or gas) with random movement of particles along complex trajectories and an almost constant flow velocity across the cross section | 5, 6, 11, 12, 15 | 128, 129, 144 |
| 21 | Surface tension of liquids | Surface tension forces, caused by the presence of surface energy, tend to reduce the interface | 6, 19, 20 | 82, 94, 129, 144 |
| 22 | Wetting | Physico-chemical interaction of liquid with solid body. The character depends on the properties of the interacting substances | 19 | 144, 129, 128 |
| 23 | Autophobic effect | When a liquid with low tension comes into contact with a high-energy solid, complete wetting first occurs, then the liquid collects into a drop, and a strong molecular layer of liquid remains on the surface of the solid | 19, 20 | 144, 129, 128 |
| 24 | Ultrasonic capillary effect | Increasing the speed and height of liquid rise in capillaries under the influence of ultrasound | 6 | 14, 7, 134 |
| 25 | Thermocapillary effect | Dependence of the speed of liquid spreading on the uneven heating of its layer. The effect depends on the purity of the liquid and its composition | 1, 6, 19 | 94, 129, 144 |
| 26 | Electrocapillary effect | Dependence of surface tension at the interface between electrodes and electrolyte solutions or ionic melts on the electric potential | 6, 16, 19 | 76, 94 |
| 27 | Sorption | The process of spontaneous condensation of a dissolved or vaporous substance (gas) on the surface of a solid or liquid. With low penetration of the sorbent substance into the sorbent, adsorption occurs, with deep penetration, absorption occurs. The process is accompanied by heat exchange | 1, 2, 20 | 1, 27, 28, 100, 30, 43, 129, 103 |
| 28 | Diffusion | The process of equalizing the concentration of each component throughout the entire volume of a mixture of gas or liquid. The rate of diffusion in gases increases with decreasing pressure and increasing temperature | 8, 9, 20, 22 | 32, 44, 57, 82, 109, 129, 144 |
| 29 | Dufour effect | The emergence of a temperature difference during diffusion mixing of gases | 2 | 129, 144 |
| 30 | Osmosis | Diffusion through a semi-permeable septum. Accompanied by the creation of osmotic pressure | 6, 9, 11 | 15 |
| 31 | Heat and mass exchange | Heat transfer. May be accompanied by mixing of the mass or caused by movement of the mass | 2, 7, 15 | 23 |
| 32 | Archimedes' Law | The action of lift on a body immersed in a liquid or gas | 5, 10, 11 | 82, 131, 144 |
| 33 | Pascal's law | Pressure in liquids or gases is transmitted evenly in all directions | 11 | 82, 131, 136, 144 |
| 34 | Bernoulli's law | Constancy of total pressure in steady laminar flow | 5, 6 | 59 |
| 35 | Viscoelectric effect | An increase in the viscosity of a polar non-conducting liquid when flowing between the capacitor plates | 6, 10, 16, 22 | 129, 144 |
| 36 | Thoms effect | Reducing friction between a turbulent flow and a pipeline when a polymer additive is introduced into the flow | 6, 12, 20 | 86 |
| 37 | Coanda effect | Deflection of the jet of liquid flowing from the nozzle towards the wall. Sometimes there is “sticking” of liquid | 6 | 129 |
| 38 | Magnus effect | The emergence of a force acting on a cylinder rotating in the oncoming flow, perpendicular to the flow and the generatrix of the cylinder | 5,11 | 129, 144 |
| 39 | Joule-Thomson effect (choke effect) | Change in gas temperature as it flows through a porous partition, diaphragm or valve (without exchange with the environment) | 2, 6 | 8, 82, 87 |
| 40 | Water hammer | Rapid shutdown of a pipeline with a moving liquid causes a sharp increase in pressure, propagating in the form of a shock wave, and the appearance of cavitation | 11, 13, 15 | 5, 56, 89 |
| 41 | Electrohydraulic shock (Yutkin effect) | Water hammer caused by pulsed electrical discharge | 11, 13, 15 | 143 |
| 42 | Hydrodynamic cavitation | The formation of ruptures in a fast flow of continuous fluid as a result of a local decrease in pressure, causing destruction of the object. Accompanied by sound | 13, 18, 26 | 98, 104 |
| 43 | Acoustic cavitation | Cavitation resulting from the passage of acoustic waves | 8, 13, 18, 26 | 98, 104, 105 |
| 44 | Sonoluminescence | Faint glow of a bubble at the moment of its cavitation collapse | 4 | 104, 105, 98 |
| 45 | Free (mechanical) vibrations | Natural damped oscillations when the system is removed from an equilibrium position. In the presence of internal energy oscillations become undamped (self-oscillations) | 1, 8, 12, 17, 21 | 20, 144, 129, 20, 38 |
| 46 | Forced vibrations | Fluctuations year by periodic force, usually external | 8, 12, 17 | 120 |
| 47 | Acoustic paramagnetic resonance | Resonant absorption of sound by a substance, depending on the composition and properties of the substance | 21 | 37 |
| 48 | Resonance | A sharp increase in the amplitude of oscillations when the forced and natural frequencies coincide | 5, 9, 13, 21 | 20, 120 |
| 49 | Acoustic vibrations | Propagation of sound waves in a medium. The nature of the impact depends on the frequency and intensity of vibrations. Main purpose - force impact | 5, 6, 7, 11, 17, 21 | 38, 120 |
| 50 | Reverberation | Aftersound caused by the transition of delayed reflected or scattered sound waves to a certain point | 4, 17, 21 | 120, 38 |
| 51 | Ultrasound | Longitudinal vibrations in gases, liquids and solids in the frequency range 20x103-109 Hz. Beam propagation with effects of reflection, focusing, formation of shadows with the ability to transmit high energy density used for force and thermal effects | 2, 4, 6, 7, 8, 9, 13, 15, 17, 20, 21, 22, 24, 26 | 7, 10, 14, 16, 90, 107, 133 |
| 52 | Wave motion | transfer of energy without transfer of matter in the form of a disturbance propagating at a finite speed | 6, 15 | 61, 120, 129 |
| 53 | Doppler-Fizeau effect | Change in oscillation frequency during mutual movement of the source and receiver of oscillations | 4 | 129, 144 |
| 54 | Standing waves | At a certain phase shift, the direct and reflected waves add up to a standing wave with a characteristic arrangement of maxima and minima of the disturbance (nodes and antinodes). There is no transfer of energy through nodes, and between neighboring nodes there is an interconversion of kinetic and potential energy. The force action of a standing wave can create a corresponding structure | 9, 23 | 120, 129 |
| 55 | Polarization | Violation of axial symmetry of a transverse wave relative to the direction of propagation of this wave. Polarization is caused by: lack of axial symmetry in the emitter, or reflection and refraction at the boundaries of different media, or propagation in an anisotropic medium | 4, 16, 19, 21, 22, 23, 24 | 53, 22, 138 |
| 56 | Diffraction | Wave bending around an obstacle. Depends on obstacle size and wavelength | 17 | 83, 128, 144 |
| 57 | Interference | Strengthening and weakening of waves at certain points in space, which occurs when two or more waves overlap | 4, 19, 23 | 83, 128, 144 |
| 58 | Moire effect | The appearance of a pattern when two equidistant systems intersect at a slight angle parallel lines. A small change in the angle of rotation leads to a significant change in the distance between the elements of the pattern | 19, 23 | 91, 140 |
| 59 | Coulomb's law | Attraction of unlike and repulsion of like electrically charged bodies | 5, 7, 16 | 66, 88, 124 |
| 60 | Induced charges | The appearance of charges on a conductor under the influence of an electric field | 16 | 35, 66, 110 |
| 61 | Interaction of bodies with fields | Changing the shape of bodies leads to a change in the configuration of the resulting electric and magnetic fields. This can be controlled by the forces acting on charged particles placed in such fields | 25 | 66, 88, 95, 121, 124 |
| 62 | Retracting the dielectric between the capacitor plates | When the dielectric is partially introduced between the plates of the capacitor, its retraction is observed | 5, 6, 7, 10, 16 | 66, 110 |
| 63 | Conductivity | Movement of free carriers under the influence of an electric field. Depends on the temperature, density and purity of the substance, its state of aggregation, external influence of forces causing deformation, and hydrostatic pressure. In the absence of free carriers, the substance is an insulator and is called a dielectric. Becomes a semiconductor when thermally excited | 1, 16, 17, 19, 21, 25 | 123 |
| 64 | Superconductivity | Significant increase in the conductivity of certain metals and alloys at certain temperatures, magnetic fields and current densities | 1, 15, 25 | 3, 24, 34, 77 |
| 65 | Law Joule-Lenz | The release of thermal energy during the passage of electric current. The value is inversely proportional to the conductivity of the material | 2 | 129, 88 |
| 66 | Ionization | The appearance of free charge carriers in substances under the influence of external factors(electromagnetic, electric or thermal fields, discharges in gases irradiated by X-rays or a flow of electrons, alpha particles, during the destruction of bodies) | 6, 7, 22 | 129, 144 |
| 67 | Eddy currents (Foucault currents) | Circular induction currents flow in a massive non-ferromagnetic plate placed in a changing magnetic field perpendicular to its lines. In this case, the plate heats up and is pushed out of the field | 2, 5, 6, 10, 11, 21, 24 | 50, 101 |
| 68 | Frictionless brake | A heavy metal plate oscillating between the poles of an electromagnet “gets stuck” when the DC current is turned on and stops | 10 | 29, 35 |
| 69 | Conductor carrying current in a magnetic field | The Lorentz force acts on electrons, which transmit force to the crystal lattice through ions. As a result, the conductor is pushed out of the magnetic field | 5, 6, 11 | 66, 128 |
| 70 | Conductor moving in a magnetic field | When a conductor moves in a magnetic field, it begins to flow electricity | 4, 17, 25 | 29, 128 |
| 71 | Mutual induction | Alternating current in one of two adjacent circuits causes the appearance of an induced emf in the other | 14, 15, 25 | 128 |
| 72 | Interaction of conductors with a current of moving electric charges | Conductors carrying current are drawn towards each other or repel each other. Moving electric charges interact in a similar way. The nature of the interaction depends on the shape of the conductors | 5, 6, 7 | 128 |
| 73 | induced emf | When a magnetic field changes or its movement in a closed conductor, an induced emf occurs. The direction of the induction current produces a field that prevents the change in magnetic flux causing induction | 24 | 128 |
| 74 | Surface effect (skin effect) | High frequency currents flow only along the surface layer of the conductor | 2 | 144 |
| 75 | Electromagnetic field | The mutual induction of electric and magnetic fields is the propagation of (radio waves, electromagnetic waves, light, x-rays and gamma rays). An electric field can also serve as its source. A special case of an electromagnetic field is light radiation (visible, ultraviolet and infrared). The thermal field can also serve as its source. The electromagnetic field is detected by thermal effect, electrical action, light pressure, activation chemical reactions | 1, 2, 4, 5, 6, 7, 11, 15, 17, 19, 20, 21, 22, 26 | 48, 60, 83, 35 |
| 76 | Charge in a magnetic field | A charge moving in a magnetic field is subject to the Lorentz force. Under the influence of this force, the charge moves in a circle or spiral | 5, 6, 7, 11 | 66, 29 |
| 77 | Electrorheological effect | Rapid reversible increase in viscosity of non-aqueous disperse systems in strong electric fields | 5, 6, 16, 22 | 142 |
| 78 | Dielectric in a magnetic field | In a dielectric placed in an electromagnetic field, part of the energy turns into heat | 2 | 29 |
| 79 | Breakdown of dielectrics | A drop in electrical resistance and thermal destruction of the material due to heating of the dielectric section under the influence of a strong electric field | 13, 16, 22 | 129, 144 |
| 80 | Electrostriction | Elastic reversible increase in body size in an electric field of any sign | 5, 11, 16, 18 | 66 |
| 81 | Piezoelectric effect | Formation of charges on the surface of a solid under the influence of mechanical stress | 4, 14, 15, 25 | 80, 144 |
| 82 | Inverse piezoelectric effect | Elastic deformation of a solid under the influence of an electric field, depending on the sign of the field | 5, 11, 16, 18 | 80 |
| 83 | Electro-caloric effect | Change in temperature of a pyroelectric when introduced into an electric field | 2, 15, 16 | 129 |
| 84 | Electrification | The appearance of electrical charges on the surface of substances. It can also be caused in the absence of an external electric field (for pyroelectrics and ferroelectrics when the temperature changes). When a substance is exposed to a strong electric field with cooling or illumination, electrets are obtained, creating an electric field around themselves | 1, 16 | 116, 66, 35, 55, 124, 70, 88, 36, 41, 110, 121 |
| 85 | Magnetization | Orientation of intrinsic magnetic moments of substances in an external magnetic field. Based on the degree of magnetization, substances are divided into paramagnets and ferromagnets. In permanent magnets, the magnetic field remains after removal of the external electrical and magnetic properties | 1, 3, 4, 5, 6, 8, 10, 11, 22, 23 | 78, 73, 29, 35 |
| 86 | Effect of temperature on electrical and magnetic properties | The electrical and magnetic properties of substances change dramatically near a certain temperature (Curie point). Above the Curie point, the ferromagnetic becomes paramagnetic. Ferroelectrics have two Curie points at which either magnetic or electrical anomalies are observed. Antiferromagnets lose their properties at a temperature called the Néel point | 1, 3, 16, 21, 22, 24, 25 | 78, 116, 66, 51, 29 |
| 87 | Magneto-electric effect | In ferroferromagnets, when a magnetic (electric) field is applied, a change in the electric (magnetic) permeability is observed | 22, 24, 25 | 29, 51 |
| 88 | Hopkins effect | Increase in magnetic susceptibility as one approaches the Curie temperature | 1, 21, 22, 24 | 29 |
| 89 | Barkhausen effect | Stepwise behavior of the magnetization curve of a sample near the Curie point with changes in temperature, elastic stress or external magnetic field | 1, 21, 22, 24 | 29 |
| 90 | Liquids that harden in a magnetic field | viscous liquids (oils) mixed with ferromagnetic particles harden when placed in a magnetic field | 10, 15, 22 | 139 |
| 91 | Piezo magnetism | The appearance of a magnetic moment when elastic stresses are applied | 25 | 29, 129, 144 |
| 92 | Magneto-caloric effect | Change in temperature of a magnet when it is magnetized. For paramagnetic materials, increasing the field increases the temperature | 2, 22, 24 | 29, 129, 144 |
| 93 | Magnetostriction | Change in the size of bodies when their magnetization changes (volumetric or linear), the object depends on temperature | 5, 11, 18, 24 | 13, 29 |
| 94 | Thermostriction | Magnetostrictive deformation when heating bodies in the absence of a magnetic field | 1, 24 | 13, 29 |
| 95 | Einstein and de Haas effect | Magnetization of a magnet causes it to rotate, and rotation causes magnetization | 5, 6, 22, 24 | 29 |
| 96 | Ferro-magnetic resonance | Selective (by frequency) absorption of electromagnetic field energy. The frequency changes depending on the field intensity and temperature changes | 1, 21 | 29, 51 |
| 97 | Contact potential difference (Volta's law) | The appearance of a potential difference when two different metals come into contact. The value depends on the chemical composition of the materials and their temperature | 19, 25 | 60 |
| 98 | Triboelectricity | Electrification of bodies during friction. The magnitude and sign of the charge are determined by the state of the surfaces, their composition, density and dielectric constant | 7, 9, 19, 21, 25 | 6, 47, 144 |
| 99 | Seebeck effect | The occurrence of thermoEMF in a circuit of dissimilar metals under the condition of different temperatures at the points of contact. When homogeneous metals come into contact, the effect occurs when one of the metals is compressed by uniform pressure or saturated with a magnetic field. The other conductor is in normal conditions | 19, 25 | 64 |
| 100 | Peltier effect | The release or absorption of heat (except Joule) when current passes through a junction of dissimilar metals, depending on the direction of the current | 2 | 64 |
| 101 | Thomson phenomenon | The release or absorption of heat (excessive over Joule heat) when current passes through an unevenly heated homogeneous conductor or semiconductor | 2 | 36 |
| 102 | Hall effect | The appearance of an electric field in a direction perpendicular to the direction of the magnetic field and the direction of the current. In ferromagnets, the Hall coefficient reaches a maximum at the Curie point and then decreases | 16, 21, 24 | 62, 71 |
| 103 | Ettingshausen effect | The occurrence of a temperature difference in the direction perpendicular to the magnetic field and current | 2, 16, 22, 24 | 129 |
| 104 | Thomson effect | Change in the conductivity of a ferromanite conductor in a strong magnetic field | 22, 24 | 129 |
| 105 | Nernst effect | The appearance of an electric field during transverse magnetization of a conductor perpendicular to the direction of the magnetic field and the temperature gradient | 24, 25 | 129 |
| 106 | Electric discharges in gases | The emergence of an electric current in a gas as a result of its ionization and under the influence of an electric field. The external manifestations and characteristics of discharges depend on control factors (gas composition and pressure, space configuration, electric field frequency, current strength) | 2, 16, 19, 20, 26 | 123, 84, 67, 108, 97, 39, 115, 40, 4 |
| 107 | Electroosmosis | Movement of liquids or gases through capillaries, solid porous diaphragms and membranes, and through the forces of very small particles under the influence of an external electric field | 9, 16 | 76 |
| 108 | Current potential | The appearance of a potential difference between the ends of capillaries and also between the opposite surfaces of a diaphragm, membrane or other porous medium when liquid is forced through them | 4, 25 | 94 |
| 109 | Electrophoresis | Movement of solid particles, gas bubbles, liquid droplets, as well as colloidal particles suspended in a liquid or gaseous medium under the influence of an external electric field | 6, 7, 8, 9 | 76 |
| 110 | Sedimentation potential | The appearance of a potential difference in a liquid as a result of the movement of particles caused by non-electrical forces (settling of particles, etc.) | 21, 25 | 76 |
| 111 | Liquid crystals | A liquid with elongated molecules tends to become cloudy in spots when exposed to an electric field and change color at different temperatures and viewing angles | 1, 16 | 137 |
| 112 | Light dispersion | Dependence of the absolute refractive index on the radiation wavelength | 21 | 83, 12, 46, 111, 125 |
| 113 | Holography | Obtaining three-dimensional images by illuminating an object with coherent light and photographing the interference pattern of the interaction of light scattered by the object with coherent radiation from the source | 4, 19, 23 | 9, 45, 118, 95, 72, 130 |
| 114 | Reflection and refraction | When a parallel beam of light falls on a smooth interface between two isotropic media, part of the light is reflected back, and the other, refracted, passes into the second medium | 4, | 21 |
| 115 | Light absorption and scattering | When light passes through matter, its energy is absorbed. Some of it is re-radiated, the rest of the energy is converted into other forms (heat). Part of the re-emitted energy spreads in different directions and forms scattered light | 15, 17, 19, 21 | 17, 52, 58 |
| 116 | Emission of light. Spectral analysis | A quantum system (atom, molecule), which is in an excited state, emits excess energy in the form of a portion of electromagnetic radiation. The atoms of each substance have a disrupted structure of radiative transitions that can be detected by optical methods | 1, 4, 17, 21 | 17, 52, 58 |
| 117 | Optical quantum generators (lasers) | Amplification of electromagnetic waves by passing them through a medium with population inversion. Laser radiation is coherent, monochromatic, with a high energy concentration in the beam and low divergence | 2, 11, 13, 15, 17, 19, 20, 25, 26 | 85, 126, 135 |
| 118 | The phenomenon of complete internal reflection | All the energy of a light wave incident on the interface between transparent media from a medium that is optically denser is completely reflected into the same medium | 1, 15, 21 | 83 |
| 119 | Luminescence, luminescence polarization | Radiation that is excessive under thermal radiation and has a duration exceeding the period of light oscillations. Luminescence continues for some time after the cessation of excitation (electromagnetic radiation, energy of an accelerated flow of particles, energy of chemical reactions, mechanical energy) | 4, 14, 16, 19, 21, 24 | 19, 25, 92, 117, 68, 113 |
| 120 | Quenching and stimulation of luminescence | Exposure to a type of energy other than the one that excites luminescence can either stimulate or extinguish luminescence. Controlling factors: thermal field, electric and electromagnetic fields (IR light), pressure; humidity, presence of certain gases | 1, 16, 24 | 19 |
| 121 | Optical anisotropy | differences in the optical properties of substances according to various directions, depending on their structure and temperature | 1, 21, 22 | 83 |
| 122 | Birefringence | On the. At the interface between anisotropic transparent bodies, light is split into two mutually perpendicular polarized beams having different propagation velocities in the medium | 21 | 54, 83, 138, 69, 48 |
| 123 | Maxwell effect | The occurrence of double refraction in a liquid flow. Determined by the action of hydrodynamic forces, flow velocity gradient, friction against the walls | 4, 17 | 21 |
| 124 | Kerr effect | The appearance of optical anisotropy in isotropic substances under the influence of electric or magnetic fields | 16, 21, 22, 24 | 99, 26, 53 |
| 125 | Pockels effect | The appearance of optical anisotropy under the influence of an electric field in the direction of light propagation. Slightly dependent on temperature | 16, 21, 22 | 129 |
| 126 | Faraday effect | Rotation of the plane of polarization of light when passing through a substance placed in a magnetic field | 21, 22, 24 | 52, 63, 69 |
| 127 | Natural optical activity | The ability of a substance to rotate the plane of polarization of light passing through it | 17, 21 | 54, 83, 138 |
Physical Effect Selection Table
List of references to the array of physical effects and phenomena
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2. Aleksandrov E.A. JTF. 36, No. 4, 1954
3. Alievsky B.D. Application of cryogenic technology and superconductivity in electrical machines and devices. M., Informstandartelektro, 1967
4. Aronov M.A., Kolechitsky E.S., Larionov V.P., Minein V.R., Sergeev Yu.G. Electrical discharges in the air at high frequency voltage, M., Energy, 1969
5. Aronovich G.V. etc. Water hammer and surge tanks. M., Nauka, 1968
6. Akhmatov A.S. Molecular physics of boundary friction. M., 1963
7. Babikov O.I. Ultrasound and its application in industry. FM, 1958"
8. Bazarov I.P. Thermodynamics. M., 1961
9. Bathers J. Holography and its application. M., Energy, 1977
10. Baulin I. Beyond the hearing barrier. M., Knowledge, 1971
11. Bezhukhov N.I. Theory of elasticity and plasticity. M., 1953
12. Bellamy L. Infrared spectra of molecules. M., 1957
13. Belov K.P. Magnetic transformations. M., 1959
14. Bergman L. Ultrasound and its application in technology. M., 1957
15. Bladergren V. Physical chemistry in medicine and biology. M., 1951
16. Borisov Yu.Ya., Makarov L.O. Ultrasound in technology of the present and future. USSR Academy of Sciences, M., 1960
17. Born M. Atomic physics. M., 1965
18. Bruening G. Physics and application of secondary electron emission
19. Vavilov S.I. About “hot” and “cold” light. M., Knowledge, 1959
20. Weinberg D.V., Pisarenko G.S. Mechanical vibrations and their role in technology. M., 1958
21. Weisberger A. Physical methods in organic chemistry. T.
22. Vasiliev B.I. Optics of polarizing devices. M., 1969
23. Vasiliev L.L., Konev S.V. Heat transfer tubes. Minsk, Science and Technology, 1972
24. Venikov V.A., Zuev E.N., Okolotin V.S. Superconductivity in energy. M., Energy, 1972
25. Vereshchagin I.K. Electroluminescence of crystals. M., Nauka, 1974
26. Volkenshtein M.V. Molecular Optics, 1951
27. Volkenshtein F.F. Semiconductors as catalysts for chemical reactions. M., Knowledge, 1974
28. Volkenshtein F.F., Radical-recombination luminescence of semiconductors. M., Nauka, 1976
29. Vonsovsky S.V. Magnetism. M., Nauka, 1971
30. Voronchev T.A., Sobolev V.D. Physical Basics electrovacuum technology. M., 1967
31. Garkunov D.N. Selective transfer in friction units. M., Transport, 1969
32. Geguzin Ya.E. Essays on diffusion in crystals. M., Nauka, 1974
33. Geilikman B.T. Statistical physics of phase transitions. M., 1954
34. Ginzburg V.L. The problem of high temperature superconductivity. Collection "The Future of Science" M., Znanie, 1969
35. Govorkov V.A. Electrical and magnetic fields. M., Energy, 1968
36. Goldelii G. Application of thermoelectricity. M., FM, 1963
37. Goldansky V.I. Moesbauer effect and its
application in chemistry. USSR Academy of Sciences, M., 1964
38. Gorelik G.S. Oscillations and waves. M., 1950
39. Granovsky V.L. Electric current in gases. T.I, M., Gostekhizdat, 1952, vol.II, M., Science, 1971
40. Grinman I.G., Bakhtaev Sh.A. Gas discharge micrometers. Alma-Ata, 1967
41. Gubkin A.N. Physics of dielectrics. M., 1971
42. Gulia N.V. Revived energy. Science and Life, No. 7, 1975
43. De Boer F. Dynamic nature of adsorption. M., IL, 1962
44. De Groot S.R. Thermodynamics of irreversible processes. M., 1956
45. Denisyuk Yu.N. Images of the outside world. Nature, No. 2, 1971
46. Deribere M. Practical use infrared rays. M.-L., 1959
47. Deryagin B.V. What is friction? M., 1952
48. Ditchburn R. Physical optics. M., 1965
49. Dobretsov L.N., Gomoyunova M.V. Emission electronics. M., 1966
50. Dorofeev A.L. Eddy currents. M., Energy, 1977
51. Dorfman Ya.G. Magnetic properties and structure of matter. M., Gostekhizdat, 1955
52. Elyashevich M.A. Atomic and molecular spectroscopy. M., 1962
53. Zhevandrov N.D. Polarization of light. M., Nauka, 1969
54. Zhevandrov N.D. Anisotropy and optics. M., Nauka, 1974
55. Zheludev I.S. Physics of dielectric crystals. M., 1966
56. Zhukovsky N.E. About water hammer in water taps. M.-L., 1949
57. Zayt V. Diffusion in metals. M., 1958
58. Zaydel A.N. Fundamentals of spectral analysis. M., 1965
59. Zeldovich Ya.B., Raiser Yu.P. Physics of shock waves and high-temperature hydrodynamic phenomena. M., 1963
60. Zilberman G.E. Electricity and magnetism, M., Nauka, 1970
61. Knowledge is power. No. 11, 1969
62. "Ilyukovich A.M. Hall effect and its application in measuring technology. J. Measuring technology, No. 7, 1960
63. Ios G. Course of theoretical physics. M., Uchpedgiz, 1963
64. Ioffe A.F. Semiconductor thermoelements. M., 1963
65. Kaganov M.I., Natsik V.D. Electrons slow down dislocation. Nature, No. 5.6, 1976
66. Kalashnikov, S.P. Electricity. M., 1967
67. Kantsov N.A. Corona discharge and its application in electrostatic precipitators. M.-L., 1947
68. Karyakin A.V. Luminescent flaw detection. M., 1959
69. Quantum electronics. M., Soviet Encyclopedia, 1969
70. Kenzig. Ferroelectrics and antiferroelectrics. M., IL, 1960
71. Kobus A., Tushinsky Y. Hall sensors. M., Energy, 1971
72. Kok U. Lasers and holography. M., 1971
73. Konovalov G.F., Konovalov O.V. Automatic control system with electromagnetic powder couplings. M., Mechanical Engineering, 1976
74. Kornilov I.I. etc. Titanium nickelide and other alloys with a “memory” effect. M., Nauka, 1977
75. Kragelsky I.V. Friction and wear. M., Mechanical Engineering, 1968
76. Brief chemical encyclopedia, vol. 5., M., 1967
77. Koesin V.Z. Superconductivity and superfluidity. M., 1968
78. Kripchik G.S. Physics of magnetic phenomena. M., Moscow State University, 1976
79. Kulik I.O., Yanson I.K. Josephson effect in superconducting tunnel structures. M., Nauka, 1970
80. Lavrinenko V.V. Piezoelectric transformers. M. Energy, 1975
81. Langenberg D.N., Scalapino D.J., Taylor B.N. Josephson effects. Collection "What are physicists thinking about", FTT, M., 1972
82. Landau L.D., Akhizer A.P., Lifshits E.M. General physics course. M., Nauka, 1965
83. Landsberg G.S. General physics course. Optics. M., Gostekhteoretizdat, 1957
84. Levitov V.I. Crown alternating current. M., Energy, 1969
85. Lengyel B. Lasers. M., 1964
86. Lodge L. Elastic fluids. M., Nauka, 1969
87. Malkov M.P. Handbook of physical and technical fundamentals of deep cooling. M.-L., 1963
88. Mirdel G. Electrophysics. M., Mir, 1972
89. Mostkov M.A. and others. Calculations of hydraulic shock, M.-L., 1952
90. Myanikov L.L. Inaudible sound. L., Shipbuilding, 1967
91. Science and Life, No. 10, 1963; No. 3, 1971
92. Inorganic phosphors. L., Chemistry, 1975
93. Olofinsky N.F. Electrical enrichment methods. M., Nedra, 1970
94. Ono S, Kondo. Molecular theory of surface tension in liquids. M., 1963
95. Ostrovsky Yu.I. Holography. M., Nauka, 1971
96. Pavlov V.A. Gyroscopic effect. Its manifestations and uses. L., Shipbuilding, 1972
97. Pening F.M. Electric discharges in gases. M., IL, 1960
98. Peirsol I. Cavitation. M., Mir, 1975
99. Instruments and experimental techniques. No. 5, 1973
100. Pchelin V.A. In a world of two dimensions. Chemistry and Life, No. 6, 1976
101. Pabkin L.I. High-frequency ferromagnets. M., 1960
102. Ratner S.I., Danilov Yu.S. Changes in proportionality and yield limits upon repeated loading. J. Factory Laboratory, No. 4, 1950
103. Rebinder P.A. Surfactants. M., 1961
104. Rodzinsky L. Cavitation versus cavitation. Knowledge is power, No. 6, 1977
105. Roy N.A. The occurrence and course of ultrasonic cavitation. Acoustic magazine, volume 3, issue. I, 1957
106. Roitenberg Y.N., Gyroscopes. M., Nauka, 1975
107. Rosenberg L.L. Ultrasonic cutting. M., USSR Academy of Sciences, 1962
108. Samerville J. M. Electric arc. M.-L., Gosenergoizdat, 1962
109. Collection "Physical metallurgy". Vol. 2, M., Mir, 1968
110. Collection "Strong electric fields in technological processes". M., Energy, 1969
111. Collection "Ultraviolet Radiation". M., 1958
112. Collection "Exoelectronic emission". M., IL, 1962
113. Collection of articles "Luminescent analysis", M., 1961
114. Silin A.A. Friction and its role in the development of technology. M., Nauka, 1976
115. Slivkov I.N. Electrical insulation and discharge in a vacuum. M., Atomizdat, 1972
116. Smolensky G.A., Krainik N.N. Ferroelectrics and antiferroelectrics. M., Nauka, 1968
117. Sokolov V.A., Gorban A.N. Luminescence and adsorption. M., Nauka, 1969
118. Soroko L. From the lens to the programmed optical relief. Nature, No. 5, 1971
119. Spitsyn V.I., Troitsky O.A. Electroplastic deformation of metal. Nature, No. 7, 1977
120. Strelkov S.P. Introduction to the theory of oscillations, M., 1968
121. Stroba J., Shimora J. Static electricity in industry. GZI, M.-L., 1960
122. Summ B.D., Goryunov Yu.V. Physico-chemical principles of wetting and spreading. M., Chemistry, 1976
123. Tables physical quantities. M., Atomizdat, 1976
124. Tamm I.E. Fundamentals of the theory of electricity. M., 1957
125. Tikhodeev P.M. Light measurements in lighting engineering. M., 1962
126. Fedorov B.F. Optical quantum generators. M.-L., 1966
127. Feyman. The nature of physical laws. M., Mir, 1968
128. Feyman lectures on physics. T.1-10, M., 1967
129. Physical encyclopedic Dictionary. T. 1-5, M., Soviet Encyclopedia, 1962-1966
130. Fransom M. Holography, M., Mir, 1972
131. Frenkel N.Z. Hydraulics. M.-L., 1956
132. Hodge F. Theory of ideally plastic bodies. M., IL, 1956
133. Khorbenko I.G. In a world of inaudible sounds. M., Mechanical Engineering, 1971
134. Khorbenko I.G. Sound, ultrasound, infrasound. M., Knowledge, 1978
135. Chernyshov et al. Lasers in communication systems. M., 1966
136. Chertousov M.D. Hydraulics. Special course. M., 1957
137. Chistyakov I.G. Liquid crystals. M., Nauka, 1966
138. Shercliffe W. Polarized light. M., Mir, 1965
139. Shliomis M.I. Magnetic fluids. Advances in physical sciences. T.112, issue. 3, 1974
140. Shneiderovich R.I., Levin O.A. Measuring plastic strain fields using the moiré method. M., Mechanical Engineering, 1972
141. Shubnikov A.V. Studies of piezoelectric textures. M.-L., 1955
142. Shulman Z.P. and others. Electrorheological effect. Minsk, Science and Technology, 1972
143. Yutkin L.A. Electrohydraulic effect. M., Mashgiz, 1955
144. Yavorsky B.M., Detlaf A. Handbook of physics for engineers and university students. M., 1965
We are surrounded by an infinitely diverse world of substances and phenomena.
Changes are constantly taking place in it.
Any changes that occur to bodies are called phenomena. The birth of stars, the change of day and night, the melting of ice, the swelling of buds on trees, the flashing of lightning during a thunderstorm, and so on - all these are natural phenomena.
Physical phenomena
Let us remember that bodies are made of substances. Let us note that during some phenomena the substances of bodies do not change, but during others they do. For example, if you tear a piece of paper in half, then, despite the changes that have occurred, the paper will remain paper. If you burn the paper, it will turn into ash and smoke.
Phenomena in which the size, shape of bodies, the state of substances may change, but substances remain the same, do not transform into others, are called physical phenomena(evaporation of water, glow of a light bulb, sound of strings musical instrument etc.).
Physical phenomena are extremely diverse. Among them there are mechanical, thermal, electrical, light and etc.
Let's remember how clouds float across the sky, an airplane flies, a car drives, an apple falls, a cart rolls, etc. In all of the above phenomena, objects (bodies) move. Phenomena associated with a change in the position of a body in relation to other bodies are called mechanical(translated from Greek “mechane” means machine, weapon).
Many phenomena are caused by alternating heat and cold. In this case, changes occur in the properties of the bodies themselves. They change shape, size, the state of these bodies changes. For example, when heated, ice turns into water, water into steam; When the temperature drops, steam turns into water, and water into ice. Phenomena associated with heating and cooling of bodies are called thermal(Fig. 35).
Rice. 35. Physical phenomenon: transition of a substance from one state to another. If you freeze drops of water, ice will form again
Let's consider electric phenomena. The word "electricity" comes from the Greek word "electron" - amber. Remember that when you quickly take off your wool sweater, you hear a slight cracking sound. If you do the same in complete darkness, you will also see sparks. This is the simplest electrical phenomenon.
To get acquainted with another electrical phenomenon, do the following experiment.
Tear small pieces of paper and place them on the table surface. Comb clean and dry hair with a plastic comb and hold it to the pieces of paper. What happened?
Rice. 36. Small pieces of paper are attracted to the comb
Bodies that are capable of attracting light objects after rubbing are called electrified(Fig. 36). Lightning during a thunderstorm, auroras, electrification of paper and synthetic fabrics are all electrical phenomena. The operation of the telephone, radio, television, and various household appliances are examples of human use of electrical phenomena.
Phenomena that are associated with light are called luminous. Light is emitted by the Sun, stars, lamps and some living creatures, such as fireflies. Such bodies are called glowing.
We see under the condition of exposure to light on the retina of the eye. In absolute darkness we cannot see. Objects that do not themselves emit light (for example, trees, grass, the pages of this book, etc.) are visible only when they receive light from some luminous body and reflect it from their surface.
The moon, which we often talk about as a night luminary, is in fact only a kind of reflector of sunlight.
By studying the physical phenomena of nature, man learned to use them in everyday life.
1. What are called natural phenomena?
2. Read the text. List what natural phenomena are named in it: “Spring has come. The sun is getting hotter and hotter. The snow is melting, streams are flowing. The buds on the trees have swelled and the rooks have arrived.”
3. What phenomena are called physical?
4. From the physical phenomena listed below, write down the mechanical phenomena in the first column; in the second - thermal; in the third - electric; in the fourth - light phenomena.
Physical phenomena: flash of lightning; snow melting; coast; melting metals; operation of an electric bell; rainbow in the sky; sunny bunny; moving stones, sand with water; boiling water.
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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 electric tools (electric drill, electric 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- these are phenomena that arise when the internal structure of the substance of physical bodies changes (the glow of the Sun and stars, an 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.
