Guerike experience in 1654. Simple experiments help to understand how Bernoulli's law works. Studying the role of air in combustion and sound transmission

Aktobe region Alginsky district Marzhanbulak secondary school

Scientific Society of Students “Zhas Kanat”

Smirnov Sergey Andreevich

Kamzin Isazhan Myrzakhanovich

Topic:

Atmosphere pressure

Direction:

Scientific and technological progress as a key link

economic growth

Section: Technics

Supervisor: Esmagambetov

Karimsak Arystanuly,

Physics teacher

Scientific adviser:

Associate Professor of Aktobe Regional

State University named after K. Zhubanov

PhD S.K. Tulepbergenov

Marzhanbulak-2013

I Introduction

(About the air shell of the Earth)

II. Research part

2.1. Evangelista Torricelli (1608–1647)

2.2. Daniel Bernoulli (1700-1782)

2.3. The historical experience of Otto von Guericke (1654)

2.4. Pascal's water barometer (1646)

2.5. Entertaining experiments on atmospheric pressure

Simple experiments help to understand how Bernoulli's law works

II. Conclusion

IV. List of used literature

Introduction

(About the air shell of the Earth)

Even in ancient times, people noticed that air exerts pressure on ground objects, especially during storms and hurricanes. He used this pressure, forcing the wind to move sailing ships, to rotate the wings of windmills. However, for a long time it was not possible to prove that air has weight. Only in the 17th century was an experiment that proved the weight of air. In Italy, in 1640, the Duke of Tuscany decided to arrange a fountain on the terrace of his palace. The water for this fountain had to be pumped from a nearby lake, but the water did not go higher than 10.3m. The duke turned to Galileo, then already a very old man, for clarification. The great scientist was confused and did not immediately find how to explain this phenomenon. And only a student of Galileo, Evangelista Torricelli in 1643 showed that air has weight. Together with V. Viviani, Torricelli conducted the first experiment on measuring atmospheric pressure, inventing the Torricelli tube (the first mercury barometer), a glass tube in which there is no air. In such a tube, mercury rises to a height of about 760 mm, he also showed that the pressure of the atmosphere is balanced by a column of water of 32 feet, or 10.3 m.

Atmospheric pressure - the pressure of the atmosphere on all objects in it and the Earth's surface. Atmospheric pressure is created by the gravitational attraction of air to the Earth.

According to the decision of the International Geophysical Union (1951), it is considered that the Earth's atmosphere consists of 5 layers: troposphere, stratosphere, mesosphere, thermosphere and exosphere. These layers do not always have clear boundaries; their thickness varies depending on the geographical latitude, the place of observation and time.

Speaking about the importance of the atmosphere, it should be noted that the atmosphere protects all life on Earth from the destructive action of ultraviolet rays, from the rapid heating of the Earth by the rays of the Sun and rapid cooling. She is also a sound transmitter. The atmosphere scatters sunlight, thereby illuminating those places where the direct rays of the Sun do not fall.

WHAT WOULD HAPPEN ON EARTH if the air atmosphere suddenly disappeared?

On Earth, a temperature of approximately -170 ° C would be established, all water spaces would freeze, and the land would be covered with an ice crust. There would be complete silence, since sound does not propagate in the void; the sky would become black, since the color of the firmament depends on the air; there would be no twilight, dawns, white nights. The twinkling of stars would stop, and the stars themselves would be visible not only at night, but also during the day (we do not see them during the day due to the scattering of sunlight by air particles). Animals and plants would die.

On the earth's surface, atmospheric pressure varies from place to place and over time. Especially important are the weather-determining non-periodic changes in atmospheric pressure associated with the emergence, development and destruction of slowly moving areas of high pressure (anticyclones) and relatively fast moving huge eddies (cyclones), in which low pressure prevails. There were fluctuations in atmospheric pressure at sea level in the range of 641 - 816 mm Hg. Art. (inside the tornado, the pressure drops and can reach a value of 560 mm Hg).

Normal atmospheric pressure is a pressure of 760 mm Hg. at sea level at 0°C. (International Standard Atmosphere - ISA) (101 325 Pa). Every morning, the weather reports broadcast atmospheric pressure data at sea level.
Why is atmospheric pressure measured on land most often reduced to sea level? The fact is that atmospheric pressure decreases with height and quite significantly. So at an altitude of 5000 m it is already about two times lower. Therefore, in order to get an idea of ​​the real spatial distribution of atmospheric pressure and to compare its magnitude in different locations and at different heights, to compile synoptic maps, etc., the pressure is reduced to a single level, i.e. to sea level.
The atmospheric pressure measured at the site of the weather station located at an altitude of 187 m above sea level, on average 16-18 mm Hg. Art. lower than down by the sea. When you rise 10.5 meters, atmospheric pressure decreases by 1 mmHg.

Atmospheric pressure does not only change with height. At the same point on the earth's surface, atmospheric pressure either increases or decreases. The reason for fluctuations in atmospheric pressure is that air pressure depends on its temperature. Air expands when heated. Warm air is lighter than cold air, so 1 m 3 of air at the same height weighs less than 1 m 3 of cold air. This means that the pressure of warm air on the earth's surface is less than that of cold air.

"Normal" atmospheric pressure is the pressure equal to the weight of a 760 mm high mercury column at a temperature of 0.0 ° C, at a latitude of 45 ° and at sea level. The basic unit of pressure in the SI system is the pascal [Pa]; 1 Pa = 1 N/m2. In the SI system 101325 Pa or 101.3 kPa or 0.1 MPa.

EVANGELISTA TORRICHELLI(1608-1647)

The Italian mathematician and physicist Evangelista Torricelli was born in Faenza in a poor family, brought up by his uncle. He studied at a Jesuit college and then received a mathematical education in Rome. In 1641, Torricelli moved to Arcetri, where he helped Galileo in processing his works. Since 1642, after the death of Galileo, he was the court mathematician of the Grand Duke of Tuscany and at the same time professor of mathematics at the University of Florence.

The most famous works of Torricelli in the field of pneumatics and mechanics. In 1643 he invented a device for measuring atmospheric pressure - the barometer.

The presence of atmospheric pressure confused people in 1638, when the idea of ​​the Duke of Tuscany to decorate the gardens of Florence with fountains failed - the water did not rise above 10.3 meters. The search for the reasons for this and experiments with a heavier substance - mercury, undertaken by Evangelista Torricelli led to the fact that in 1643 he proved that air has weight. With his rather simple experiment, Evangelista Torricelli measured atmospheric pressure and made the first conclusions about the pressure of a liquid column, which are fixed in the basic law of hydrostatics. In the experiment, staged in 1643, a thin glass tube sealed at one end was used, which was filled with mercury, after which it was turned over and lowered with its open end into a glass bath, also filled with mercury (see Fig.). Only a part of the mercury flowed into the trough, and a so-called "flutter" appeared at the sealed end of the tube. the Torricelli void (in fact, this “void” was filled with saturated mercury vapor, but their pressure at room temperature is much less than atmospheric, so this area can be approximately called a void).

The observed effect indicated that the mercury was kept from being completely poured out by some force acting from the lower end of the tube. This force created atmospheric pressure, which opposes the weight of the liquid column.

At present, atmospheric pressure, equal to the pressure of a mercury column 760 mm high at a temperature of 0 ° C, is commonly called normal atmospheric pressure.

Substituting in this formula the values ​​\u200b\u200bof p \u003d 13595.1 kg / m 3 (density of mercury at 0 ° C), g \u003d 9.80665 m / s 2 (gravitational acceleration) and h \u003d 760 mm \u003d 0.76 m (column height mercury corresponding to normal atmospheric pressure), we get the following value: P \u003d p gh \u003d 13595.1 kg / m 3 X 9.80665 m / s 2 X 0.76 m \u003d 101 325 Pa.

This is normal atmospheric pressure.

The column of mercury in the tube always had the same height, approximately 760 mm. Hence the unit of pressure is a millimeter of mercury (mm Hg). According to the formula above, we get that in Pascals

Torricelli found that the height of the mercury column in his experiment did not depend on either the shape of the tube or its inclination. At sea level, the height of the mercury column has always been about 760mm.

The scientist suggested that the height of the liquid column is balanced by air pressure. Knowing the height of the column and the density of the liquid, one can determine the pressure of the atmosphere. The correctness of Torricelli's assumption was confirmed in 1648 by Pascal's experiment on Mount Puy de Dome. Pascal proved that a smaller column of air exerts less pressure. Due to the attraction of the Earth and insufficient speed, air molecules cannot leave the near-Earth space. However, they do not fall to the surface of the Earth, but hover above it, because. are in continuous thermal motion.

Due to thermal motion and the attraction of molecules to the Earth, their distribution in the atmosphere is uneven. At low altitudes, every 12 m of ascent, atmospheric pressure is reduced by 1 mm Hg. At high altitudes, this pattern is violated.

This happens because the height of the air column that exerts pressure decreases as it rises. In addition, the air in the upper atmosphere is less dense.

DANIEL BERNULLI(1700-1782)

In the 18th century, mathematician and mechanic, academician of the St. Petersburg Academy of Sciences Daniil Bernoulli conducted an experiment with a pipe of different thickness, through which a liquid flowed. Let us assume that the liquid flows through a horizontal pipe, the cross section of which is different in different places. Let's mentally single out several sections in the pipe, their areas: S1 S2, S3. S4.

For some period of time t, a liquid of the same volume must pass through each of these sections. All the liquid that passes through the first section in time t must pass through all other segments of smaller diameter in the same time. If this were not the case, and less liquid passed through the section with area S3 in time t than through the section with area S1, then the excess liquid should have accumulated somewhere. But the liquid fills the pipe, and there is nowhere for it to accumulate. Note that we assume that the fluid is incompressible and has the same volume everywhere. How can a liquid that has flowed through the first section "have time" to flow through a much smaller section with area S3 in the same time? Obviously, for this, when passing through the narrow parts of the pipe, the velocity of the fluid must be greater than when passing through the wide ones.

A tube - a manometer - is vertically soldered in sections of the pipe of different thicknesses. In the narrow places of the pipe, the height of the liquid column is less than in the wide ones. This means that there is less pressure in narrow places.

The pressure of the fluid flowing in the pipe is greater in those parts of the pipe where the speed of its movement is less, and, conversely, in those parts where the speed is greater, the pressure is less. This is the Law of Bernoulli.

In the wide part of the pipe, the velocity is less than in the narrow part as many times as the cross-sectional area 1 is greater than 2.

Let the fluid flow without friction through a pipe of variable cross section:

In other words, the same volumes of liquid pass through all sections of the pipe, otherwise the liquid would either have to break somewhere or compress, which is impossible. During t through the section S1 pass volume

, and through the section S 2 - volume. But since these volumes are equal, then

The fluid flow rate in a pipe of variable cross section is inversely proportional to the cross sectional area.

If the cross-sectional area increased by 4 times, then the velocity decreased by the same amount and vice versa, by how many times the pipe section decreased, the velocity of the liquid or gas flow increased by the same amount. Where is this phenomenon of speed change observed? For example, on a river flowing into the sea, there is a decrease in speed, water from a bath - the speed increases, we observe a turbulent flow of water. If the speed is low, then the liquid flows as if divided into layers (“laminia” - layer). The flow is called laminar.

So, we found out that when a liquid flows from a narrow part to a wide one or vice versa, the speed changes, therefore, the liquid moves with acceleration. What is causing the acceleration? (Force (Newton's second law)). What force imparts acceleration to the liquid? This force can only be the difference between the pressure forces of the liquid in the wide and narrow parts of the pipe.

Bernoulli's equation shows that the pressure of a flowing liquid or gas is greater where the velocity is less, and the pressure is less where the flow velocity is greater. This seemingly paradoxical conclusion is confirmed by direct experiments.

This conclusion was first made by Academician of the St. Petersburg Academy of Sciences Daniil Bernoulli in 1726 and the law now bears his name.

It remains valid for the movement of liquids and for gases not limited by the walls of the pipe - in the free flow of liquid.

THE HISTORICAL EXPERIENCE OF OTTO VON GERICKE (1654)

The German physicist Otto von Guericke (1602-1686) came to the conclusion about the existence of atmospheric pressure independently of Torricelli (whose experiments he learned about nine years late). While somehow pumping air out of a thin-walled metal ball, Guericke suddenly saw how this ball was flattened. Reflecting on the cause of the accident, he realized that the flattening of the ball was due to the pressure of the surrounding air.

Having discovered atmospheric pressure, Guericke built a water barometer near the facade of his house in the city of Magdeburg, in which a figurine in the form of a man floated on the surface of the liquid, indicating the divisions made on the glass.

In 1654, Guericke, wishing to convince everyone of the existence of atmospheric pressure, made the famous experiment with the "Magdeburg hemispheres". The demonstration was attended by Emperor Ferdinand III and members of the Regensburg Reichstag. In their presence, air was pumped out of the cavity between two metal hemispheres stacked together. At the same time, atmospheric pressure forces pressed these hemispheres so strongly against each other that several pairs of horses could not separate them. Below is the famous drawing by G. Schott, which depicts 16 horses, 8 on each side of the metal Magdeburg hemispheres, between which a vacuum. The hemispheres are pressed against each other by nothing more than atmospheric pressure, and this force is so great that even such a decent harness cannot tear the hemispheres apart from each other.

PASCAL'S WATER BAROMETER (1646)

Torricelli's experiments interested many scientists - his contemporaries. When the French scientist Blaise Pascal found out about them, he repeated them with different liquids (oil, wine and water).

The figure shows a water barometer created by Pascal in 1646. The water column, which balances the pressure of the atmosphere, turned out to be much higher than the mercury column. It turned out to be equal to 10.3 meters.

ENTERTAINING EXPERIMENTS ON ATMOSPHERIC PRESSURE

Consider a series of experiments related to the action of atmospheric pressure.
Air has weight:

With the help of a vacuum pump, we pump out air from a glass flask and balance the flask on a lever balance. We open the tap and let air into the flask, and we see that the balance of the scales has been disturbed. This experience convincingly shows that air has weight. Therefore, air exerts pressure on all objects near the surface of the Earth. Atmospheric pressure is the pressure of the atmosphere on all objects in it and the Earth's surface. Atmospheric pressure is created gravitational attraction air to earth and thermal motion air molecules.

Inflating a baby balloon by pumping out air!?:

Why, when air is pumped out from under the bell of the pump located on its plate, the chamber of a child's balloon with a well-knotted process begins to inflate, as it were?

Answer: Inside the chamber, the pressure remains constant (atmospheric) all the time, while outside it decreases. Due to the pressure difference, the balloon "inflates".

Experiment with a test tube with a stoppered rubber stopper:

A similar experiment can be performed with a test tube with a stoppered rubber stopper. When air is pumped out from under the bell, the cork flies out of the bottle?! Why? Answer: The cork flies out due to the pressure difference: the pressure in the flask is atmospheric, and outside it, under the bell, it is reduced.

Another experiment with test tubes:

We take two such tubes so that one of them can freely enter the other. Pour a little water into the wide one, and then insert a short narrow test tube into it. If we now turn the test tubes over, we will see that the narrow test tube will not fall, but, on the contrary, as the water flows out, it will rise up, being drawn into the wide test tube.
Why is this happening?

Answer: The pressure inside a large test tube is less than the outer one, due to the outflow of water, a void has formed there, so atmospheric pressure drives a small test tube inside a large one.

Inverted glass:

Fill an ordinary glass to the brim with water. We cover it with a piece of paper, tightly covering it with our hand, turn it upside down with paper. Carefully remove your hand, holding the glass by the bottom. Water does not pour out. Why is this happening?

Answer: Air pressure holds water. Air pressure spreads equally in all directions (according to Pascal's law), which means that it also goes up. The paper only serves to keep the surface of the water perfectly flat.

Experience with the Magdeburg hemispheres:

We take two home-made iron hemispheres (diameter 10 cm). Lubricate the edges of the hemispheres with liquid machine oil, lightly press them against each other and pump out air using a vacuum pump. Let's close the faucet and, as shown in the photo, hang a two-kilogram weight on them, the hemispheres do not come off. There is no air inside the hemisphere, or there is not enough of it, therefore, the external atmospheric pressure presses them tightly against each other and does not allow them to burst. In 1654, the German physicist Otto von Guericke, wanting to convince everyone of the existence of atmospheric pressure, made a famous experiment in Magdeburg with similar hemispheres about one meter in diameter, where eight pairs of horses could not break them. In honor of this famous experiment, such hemispheres were called "Magdeburg hemispheres".

Torricelli barometer:

We take a thin glass tube, closed at one end, fill it with bluish water (for better visibility) and then turn it over and lower it with the open end into a glass bath. In this case, some of the water will pour out onto the cup until the neck of the tube closes and the water does not pour out further, since it is held by atmospheric pressure.

The Italian mathematician and physicist Evangelista Torricelli for the first time in 1643 set up a similar experiment with mercury: a column of mercury in a tube had a height of approximately 760 mm. Such an instrument was later called a mercury barometer. The French scientist Blaise Pascal in 1646 did a similar experiment with water, the column of water, which balances the pressure of the atmosphere, turned out to be much higher than the column of mercury. It turned out to be equal to 10.3 meters.

The photo shows how to make a simple bird drinker using atmospheric pressure. To do this, it is enough to somehow vertically fix a plastic bottle filled with water with the neck down and place flat dishes from below. When the birds drink water, the water from the bottle will pour out enough to close the neck of the bottle.

How does a syringe work?

As you can see in the photo, the water moves behind the piston. Forces liquid into the syringe at atmospheric pressure.

We transfer water with a holey mug:

Is it possible to transfer water with a leaky mug? We answer yes you can! To do this, it is enough to close the top of the mug tightly with something and you can transfer water, atmospheric pressure will prevent the water from pouring out. We made such a device for the experiment, as you can see in the photo, from an empty tin can.

SIMPLE EXPERIENCES HELP YOU UNDERSTAND HOW BERNULLI'S LAW WORKS:

Experience 1:

We press the plates and petals pushing them away with an air jet!:

When we blow air between the plates and petals, instead of diverging, they are pressed against each other. This happens because between the plates and the petals the air speed increases, and the pressure between them decreases compared to atmospheric pressure. This pressure difference presses them.

Experience 2: A floating ball:

E If you put a light tennis ball into a jet of air, it will “dance” in the jet, even if it is slightly inclined. Why? The speed of the air jet created by the hair dryer is high, which means that the pressure in this area is low. The air speed in the whole room is low, which means the pressure is high. The high pressure area will prevent the ball from falling out of the low pressure area.

Experiment 3: Collision of two boats:

Z let's launch two boats in the same direction. They will start to approach and collide.

Between the sides it turns out, as it were, a water channel.

In a narrow place between the boats, the pressure is lower than in the space around them, the higher pressure of the surrounding water brings them together and pushes them together.

History reference: It was Bernoulli's law that made it possible to understand why, in 1912, the small armored cruiser "Gauk", passing by the largest ship in the world, "Olympic", when the ships took a position, as shown in the figure, as if obeying some invisible force, "Gauk" suddenly turned his nose to the "Olympic", and not obeying the helm, moved straight towards it and made a large hole in the side of the "Olympic". In the same year, the twin of the Olympic, the Titanic, sank, which could not avoid a collision with an iceberg.

What do you think caused the shipwreck? In this case, a channel formed between the ships moving in the same direction with water flowing in the opposite direction. And in a stream of water, the pressure is less than around it, in a resting ocean. The huge pressure difference caused the lighter ship to crash into the “floating city” Olympic, so the Titanic could not avoid colliding with the iceberg. This example shows that the Bernoulli phenomenon occurs not only in the atmosphere, but also in the sea.

CONCLUSION

We live at the bottom of a vast ocean of air called the atmosphere. Word is ("atmos" - air, "sphere" - a ball) introduced into the Russian language M.Yu. Lomonosov.

If a person does not feel air pressure, because the external and internal pressures are balanced, then the pressure manifests itself in a situation where there is no pressure nearby or it is very small.

We have collected a lot of historical and theoretical material on atmospheric pressure. Qualitative experiments were carried out, which confirmed the known properties of atmospheric pressure.

However, the idea of ​​our work is not to learn how to measure atmospheric pressure, but to show that it exists. On an industrial basis, only one Pascal's Ball device is produced to demonstrate the law of pressure propagation inside liquids and gases. We have made many simple instruments based on the action of atmospheric pressure and showing the existence of atmospheric pressure. On the basis of these devices, one can introduce the concept of atmospheric pressure and show the effect of atmospheric pressure in entertaining experiments.

For the manufacture of devices do not require scarce materials. The devices of the instruments are extremely simple, the dimensions and parameters do not require special accuracy, they are in good agreement with the existing instruments of the physics classroom.

The results of our work can be used to demonstrate the properties of atmospheric pressure in the classroom and optional classes in physics.

LITERATURE

1. "Experimental-experimental and practical orientation in teaching physics" Compiled by: K.A.Esmagambetov; M.G. Mukashev, Aktobe, 2002, 46 pages.

2. K.A. Esmagambetov "Okytudyn үsh olshemdіk adistemelik zhүyesi: experimental sertteu men nәtizhe". Aktobe, 2010.- 62 bet.

3. P.L. Golovin. School physical and technical circle. M.: "Enlightenment" 1991

4. S.A. Khoroshavin. Physical and technical modeling. M.: Enlightenment 1988. -207 p.

5. Modern physics lesson in high school. Edited by V.G. Razumovsky,

L.S. Khizhnyakova M.: "Enlightenment" 1983 -224 pages.

6. E.N. Goryachkin. Laboratory equipment and handicraft techniques. M .: "Enlightenment"

1969. -472 pp.

7. Journal of Physics at school No. 6, 1984. SA Khoroshovin "Demonstration experiment as a source of students' knowledge" p.56.

He studied law, mathematics and mechanics in Leipzig, Jena and Leiden. For some time he served as an engineer in Sweden. From 1646 he was burgomaster of Magdeburg. In 1650, he invented vacuum pumping and applied his invention to study the properties of vacuum and the role of air in the combustion process and for human breathing. In 1654 he conducted a famous experiment with the Magdeburg hemispheres, which proved the presence of air pressure; established the elasticity and weight of air, the ability to sustain combustion, to conduct sound.

In 1657 he invented a water barometer, with the help of which in 1660 he predicted an impending storm 2 hours before its appearance, thus going down in history as one of the first meteorologists.

In 1663 he invented one of the first electrostatic generators that produce electricity by friction - a ball of sulfur rubbed by hand. In 1672, he discovered that a charged ball crackles and glows in the dark (he was the first to observe electroluminescence). In addition, he discovered the property of electrical repulsion of unipolarly charged objects.

Scientific activity

Despite such a clear inclination towards scientific studies, Otto von Guericke never shied away from the civic duties assigned to him by his native city and, having assumed the honorary position of burgomaster of the city of Magdeburg, almost at the most troubled time for the country, was forced to constantly absent himself to perform various diplomatic missions; if we also add that he was in this troublesome position for 32 years, and before that he had been in captivity, and in military service, and was engaged in the construction of fortifications and bridges, then one cannot help but be surprised at the perseverance with which he indulged in his free days and hours his favorite occupations in physics and such a significant number of inventions and new experiments with which he enriched science and a detailed description of which he left in his famous book: “Ottonis de Guericke Experivmenta Nova (ut vacantus) Magdeburgica”.

As a physicist, Guericke was first and foremost an experimenter who fully understood the scientific significance of experiment, which in his time could be considered a sign of genius. In the 17th century it was still very difficult to abandon the scholastic trend that had dominated science for so long and accustom one's mind to an independent assessment of observed phenomena. Among scholars, only a few could say like Guericke:

Vacuum experiments

Knowing nothing about the invention of the mercury barometer (1643) and about the so-called Torricellian void, Guericke persistently sought to destroy the old philosophical dispute about empty space through experience. And so, about 1650, the result of this perseverance is the invention of the air pump.

Guericke, as you know, at first did not consider it possible to pump out air directly and wanted to form an empty space in a hermetically sealed barrel by removing the water that filled it. To this end, he attached a pump to the bottom of the barrel, thinking that only with such an arrangement of the device would water follow the piston of the pump due to its gravity. From this we see that at first Guericke did not yet have a definite concept of atmospheric pressure and, in general, of the elasticity of air. When this first attempt failed, since outside air hissed into the resulting void through the cracks and pores of the barrel, Guericke tried to place his barrel in another, also filled with water, suggesting in this way to protect the void from the air rushing into it from outside. But this time the experiment turned out to be unsuccessful, because the water from the outer barrel, under the influence of atmospheric pressure, flowed through the pores into the inner one and filled the void. Then, finally, Guericke decided to apply the pump to the direct pumping out of air from a copper spherical vessel, still adhering to his false assumption that air, like water, can follow the piston of the pump only due to its gravity, therefore, now the pump was screwed at the bottom of the vessel and placed vertically. The result of the pumping out was completely unexpected and frightened everyone present: the copper ball could not withstand the external pressure and was crumpled and flattened with a crash. This forced Guericke to prepare stronger and more regular tanks for the next experiments. The inconvenient location of the pump soon forced Guericke to arrange a tripod special for the entire device and attach a lever to the piston; thus the first air pump was built, named Antlia pneumatica by the author. Of course, the device was still very far from perfect and required at least three people to manipulate the piston and taps immersed in water in order to better isolate the resulting void from the outside air.

He studied law, mathematics and mechanics in Leipzig, Jena and Leiden. For some time he served as an engineer in Sweden. From 1646 he was burgomaster of Magdeburg. In 1650, he invented vacuum pumping and applied his invention to study the properties of vacuum and the role of air in the combustion process and for human breathing. In 1654 he conducted a famous experiment with the Magdeburg hemispheres, which proved the presence of air pressure; established the elasticity and weight of air, the ability to sustain combustion, to conduct sound.

In 1657 he invented a water barometer, with the help of which in 1660 he predicted an impending storm 2 hours before its appearance, thus going down in history as one of the first meteorologists.

In 1663 he invented one of the first electrostatic generators that produce electricity by friction - a ball of sulfur rubbed by hand. In 1672, he discovered that a charged ball crackles and glows in the dark (he was the first to observe electroluminescence). In addition, he discovered the property of electrical repulsion of unipolarly charged objects.

Scientific activity

Despite such a clear inclination towards scientific studies, Otto von Guericke never shied away from the civic duties assigned to him by his native city and, having assumed the honorary position of burgomaster of the city of Magdeburg, almost at the most troubled time for the country, was forced to constantly absent himself to perform various diplomatic missions; if we also add that he was in this troublesome position for 32 years, and before that he had been in captivity, and in military service, and was engaged in the construction of fortifications and bridges, then one cannot help but be surprised at the perseverance with which he indulged in his free days and hours his favorite occupations in physics and such a significant number of inventions and new experiments with which he enriched science and a detailed description of which he left in his famous book: “Ottonis de Guericke Experivmenta Nova (ut vacantus) Magdeburgica”.

As a physicist, Guericke was first and foremost an experimenter who fully understood the scientific significance of experiment, which in his time could be considered a sign of genius. In the 17th century it was still very difficult to abandon the scholastic trend that had dominated science for so long and accustom one's mind to an independent assessment of observed phenomena. Among scholars, only a few could say like Guericke:

Vacuum experiments

Knowing nothing about the invention of the mercury barometer (1643) and about the so-called Torricellian void, Guericke persistently sought to destroy the old philosophical dispute about empty space through experience. And so, about 1650, the result of this perseverance is the invention of the air pump.

Guericke, as you know, at first did not consider it possible to pump out air directly and wanted to form an empty space in a hermetically sealed barrel by removing the water that filled it. To this end, he attached a pump to the bottom of the barrel, thinking that only with such an arrangement of the device would water follow the piston of the pump due to its gravity. From this we see that at first Guericke did not yet have a definite concept of atmospheric pressure and, in general, of the elasticity of air. When this first attempt failed, since outside air hissed into the resulting void through the cracks and pores of the barrel, Guericke tried to place his barrel in another, also filled with water, suggesting in this way to protect the void from the air rushing into it from outside. But this time the experiment turned out to be unsuccessful, because the water from the outer barrel, under the influence of atmospheric pressure, flowed through the pores into the inner one and filled the void. Then, finally, Guericke decided to apply the pump to the direct pumping out of air from a copper spherical vessel, still adhering to his false assumption that air, like water, can follow the piston of the pump only due to its gravity, therefore, now the pump was screwed at the bottom of the vessel and placed vertically. The result of the pumping out was completely unexpected and frightened everyone present: the copper ball could not withstand the external pressure and was crumpled and flattened with a crash. This forced Guericke to prepare stronger and more regular tanks for the next experiments. The inconvenient location of the pump soon forced Guericke to arrange a tripod special for the entire device and attach a lever to the piston; thus the first air pump was built, named Antlia pneumatica by the author. Of course, the device was still very far from perfect and required at least three people to manipulate the piston and taps immersed in water in order to better isolate the resulting void from the outside air.

Robert Boyle, who made significant improvements to the pneumatic machine, considered Otto von Guericke to be its real inventor. And although Guericke, at the beginning of his research, misinterpreted the action of his device (by the weight, and not by the elasticity of the air enclosed in the tank), nevertheless, he apparently well understood the impossibility of achieving absolute emptiness through an air pump.

Gerike should be considered the inventor of only the air rarefaction pump: pressure pumps were known in antiquity, and their invention is attributed to Ktesibius, who lived in the 2nd century BC. e. in Alexandria. Blow guns were also already known to Gerika, but he came to the concept of air elasticity only after the construction of his pump, based on many experiments. Obviously, this question, so elementary today, must be considered one of the most difficult for that time, and the establishment of the Boyle-Mariotte law around 1676 is one of the most important conquests of the human mind of that time.

The experiments that Guericke showed publicly with his air pumps brought him great fame. Various dignitaries came to Magdeburg on purpose to see for themselves the fairness of all these novelties. The well-known experience with the Magdeburg hemispheres was shown in 1654 in Regensburg during the Reichstag. Experience has proven the presence of air pressure. Other of his pneumatic experiments are still repeated in school physics lessons and are described in textbooks.

One of Guericke's experiments was as follows: a ball filled with air, and another, from which the air was previously pumped out, communicated through a tube; then the air from the first ball entered the empty ball at such a rapid speed that Gerika showed the similarity of this phenomenon with earthly storms.

The experiment with a tightly tied bull bladder that swells and finally bursts under the bell of a pneumatic machine was also then invented to demonstrate the elasticity of air. Having once understood these phenomena of elasticity, Guericke went further with quick steps, and his conclusions were always distinguished by a strictly logical sequence. Soon he began to prove that since air has weight, the atmosphere produces pressure on itself, and the lower layers of air at the surface of the earth, as the most compressed, should be the most dense. To demonstrate this difference in elasticity, he came up with the following wonderful experiment: a ball filled with air was locked with a crane and transferred to a high tower; there, when the tap was opened, it was noticed that part of the air came out of the ball to the outside; on the contrary, if the ball was filled with air and locked at a height, and then moved down, then the air rushed into the ball when the tap was opened. Guericke understood very well that a necessary condition for the credibility of this experiment was the constancy of temperature, and he took care that the air-borne ball was "equally heated both at the bottom and at the top of the tower." Based on such experiments, he came to the conclusion that "the weight of a certain volume of air is something very relative," since this weight depends on the height above the earth's surface. The result of all these considerations was the device of a "manometer", that is, "an instrument designed to measure the difference in density, or in weight, of a given volume of air." Now we call this term a device used to measure the elasticity (pressure) of gases in millimeters of mercury. Robert Boyle, who described it in detail, gave the device Guericke the name "static barometer", or "baroscope", which is retained by him in our time. This device, based on the law of Archimedes, consists of a large hollow ball, balanced by means of a balance beam with a small weight. In Guericke's baroscope, the ball had a diameter of about 3 meters. It was first described in a letter from Guericke to Caspar Schott () in 1661.

water barometer

Earlier than this, around 1657, Guericke set up his grandiose water barometer. During a stay in Regensburg in 1654, he learned (from a monk, Magnus) about the experiments of Torricelli. It is possible that this important news prompted him to take up the same question, or perhaps he independently came to the invention of his water barometer, the device of which was closely connected with his previous pneumatic experiments. Be that as it may, this device already existed in 1657, since there are indications that from that very time its readings depended on the state of the weather. It consisted of a long (20 Mg. cubits) copper tube attached to the outer wall of the three-story house of Gerike. The lower end of the tube was immersed in a vessel with water, and the upper end, supplemented with a glass tube, was equipped with a tap and could be connected to an air pump. When the air was pumped out, the water rose in the tube to a height of 19 cubits; then the tap was closed, and the barometer was disconnected from the pump. Soon, with the help of this device, Guericke found that the atmospheric pressure is constantly changing, which is why he called his barometer the words Semper vivum. Then, noticing the relationship between the height of the water in the tube and the state of the weather, he named it Wettermannchen. For greater effect, on the surface of the water in a glass tube was a float, which looked like a human figure with an outstretched hand, which pointed to a table with inscriptions corresponding to various weather conditions; the rest of the device was deliberately masked with wooden sheathing. In his book, Guericke gave his barometer the name Anemoscopium. In 1660, he brought all the inhabitants of Magdeburg into extreme indignation, predicting a strong storm 2 hours before it began.

Studying the role of air in combustion and sound transmission

Having chosen air as the subject of his research, Guericke tried to prove by experience the necessity of his participation in such phenomena as the transmission of sound over a distance and combustion. He invented the well-known experiment with a bell under the hood of an air pump, and on the issue of combustion, he was significantly ahead of his contemporary philosophers, who had the most vague ideas about this phenomenon. So, for example, Rene Descartes in 1644 tried to prove by reasoning that a lamp can burn in a hermetically sealed space for as long as desired.

Convinced that a candle cannot burn in a tank from which air is pumped out, Guericke proved, using a device specially designed for this purpose, that the flame devours air, that is, that some part of the air (in his opinion, about 1/10) is destroyed by combustion. Let us recall that in this era there was still no chemical information, and no one had any idea about the composition of the air; it is not surprising, therefore, that Guericke could not explain the fact that part of the air was absorbed during combustion and only said that the flame spoils the air, because his candle went out relatively quickly in an enclosed space. In any case, he was much closer to the truth than those chemists of the 17th century who created the phlogiston hypothesis.

Study of the effect of heat on air

Guericke also studied the effect of heat on air, and although he did not make any significant improvements in the device of his air thermometer compared to the instruments then known (which in his time in Italy were called caloris mensor), nevertheless, we can safely say that he was first time meteorologist. Without touching on the controversial and essentially unimportant question of the invention of the thermometer, which is most often attributed to Galileo, but also to Drebbel and the doctor Sanctorius, we only note that its original form was extremely imperfect: firstly, because the readings of the device were not influenced by only temperature, but also atmospheric pressure, and secondly, due to the lack of a specific unit (degree) for comparing thermal effects.

The thermometer (air) of that time consisted of a tank with a tube immersed with an open end in a vessel with water; the level of water raised in the tube obviously varied depending on the air temperature in the tank and on the external atmospheric pressure. It is strange that Guericke, to whom this last influence should have been well known, did not pay attention to it, at least this influence was not eliminated in his thermometer. The device itself, designed exclusively for observing changes in the temperature of the outside air and therefore, like a barometer, placed on the outer wall of the house, consisted of a Siphon (metal) tube filled to about half with alcohol; one end of the tube communicated with a large ball containing air, the other was open and contained a float, from which a thread went through a block; at the end of the thread, a wooden figurine swayed freely in the air, pointing with its hand at a scale with 7 divisions. All the details of the device, except for the ball, which flaunted the inscription Perpetuum mobile, figures and scales, were also covered with boards. The extreme points on the scale were marked with the words: magnus frigus and magnus calor. The middle line was of particular importance, so to speak, climatic: it had to correspond to the air temperature at which the first autumn night frosts appear in Magdeburg.

From this we can conclude that although the first attempts to mark 0 ° on the thermometer scale belonged to the Florentine Academy (Del Cimento), famous in the history of experimental physics, Guericke also understood how important and necessary it was to have at least one constant point on the thermometric scale, and, as we we see that he was trying to take a new step forward in this direction, choosing an arbitrary line corresponding to the first autumn frosts to regulate his thermometer.

The study of electricity

Now let's move on to another area of ​​physics, in which the name of Guericke also enjoys well-deserved fame. We are talking about electricity, which at that time, called, so to speak, to life by Gilbert's experimental studies, represented in the form of a few fragmentary facts only an insignificant and uninteresting germ of that grandiose force that was destined to win the attention of the entire civilized world and entangle the globe. network of conductors.

Otto von Guericke is sometimes called only a witty inventor of physical instruments, striving to become famous among his contemporaries for his grandiose experiments and caring little about the progress of science. But Ferdinand Rosenberger (1845-1899) in his "History of Physics" quite rightly notes that such a reproach is without any foundation, because Guericke did not at all have the exclusive goal of surprising the public. He was always guided by purely scientific interests and deduced from his experiments not fantastic ideas, but real scientific conclusions. The best proof of this is his experimental studies of the phenomena of static electricity, which at that time - we repeat - very few people were interested in.

Wishing to repeat and test Gilbert's experiments, Guericke invented a device for obtaining an electrical state, which, if it cannot be called an electric machine in the true sense of the word, because it lacked a capacitor to collect electricity developed by friction, nevertheless served as a prototype for all late staged electrical discoveries. First of all, this should include the discovery of electrical repulsion, which was unknown to Hilbert.

To develop the electrical state, Guericke prepared a rather large ball of sulfur, which, by means of an axle threaded through, was set in rotation and rubbed simply with a dry hand. Having electrified this ball, Guericke noticed that the bodies attracted by the ball repel after being touched; then he also noticed that a feather freely floating in the air, attracted and then repelled from the ball, is attracted by other bodies. Guericke also proved that the electrical state is transmitted along a thread (linen); but at the same time, not yet knowing anything about insulators, he took the length of the thread only one cubit and could only give it a vertical arrangement. He was the first to observe an electric glow in the dark on his sulfur ball, but he did not receive a spark; he also heard a faint crackling “in the sulfur ball” when he brought it close to his ear, but did not know what to attribute it to.

The study of magnetism

In the field of magnetism, Guericke also made several new observations. He found that vertical iron bars in window bars were magnetized by themselves, representing the north poles above and the south poles below, and showed that it was possible to slightly magnetize an iron strip by placing it in the direction of the meridian and hitting it with a hammer.

Refinements in the field of astronomy

He also studied astronomy. He was a supporter of the heliocentric system. He developed his own cosmological system, which differed from the Copernican system in the assumption of the presence of an infinite space in which fixed stars are distributed. He believed that outer space is empty, but between celestial bodies there are long-range forces that regulate their movement.

In philately

Germany stamp 1936

GDR stamp 1977

GDR stamp 1969

Germany stamp 2002

The German physicist, engineer and philosopher Otto von Guericke was born in Magdeburg on November 20, 1602. After graduating from the city college, he continued his studies at the universities of Leipzig, Helmstadt, Jena and Leiden.

For some time he served as an engineer in Sweden. He was especially interested in physics, applied mathematics, mechanics and fortification. Gerike's youth came at the beginning of the brutal Thirty Years' War. As a strategically important center of eastern Germany, Magdeburg changed hands several times, and in 1631 was almost completely destroyed. Gerika, as a member of the city council, had to show not only outstanding engineering, but also outstanding diplomatic skills during these years. For merits in the defense and restoration of Magdeburg in 1646, he was elected burgomaster of the city and held this post for 30 years.

Far from being an armchair scientist, Guericke was interested in the natural sciences throughout his life. To test Aristotle's postulate - nature does not tolerate voids - he invented an air pump, with the help of which in 1654 he carried out his famous experiment with the Magdeburg hemispheres. To carry out the experiment, two copper hemispheres with a diameter of 14 inches (35.6 cm) were made, one of which was equipped with a tube for pumping out air. These hemispheres were put together, and a leather ring soaked in melted wax was placed between them. Then, with the help of a pump, air was pumped out of the cavity formed between the hemispheres. On each of the hemispheres there were iron rings to which two teams of horses were harnessed. In 1654, in Regensburg, von Guericke demonstrated the experiment to the Reichstag in the presence of Emperor Ferdinand III. After pumping out of the sphere of air, 16 horses, 8 on each side, could not break the hemispheres, however, when air was let into the hemispheres, they disintegrated without effort. It is not known whether the horses were used on both sides for greater entertainment or out of ignorance of the physicist himself, because it was possible to replace half of the horses with a fixed mount, without losing the force of impact on the hemispheres. In 1656 Guericke repeated the experiment in Magdeburg, and in 1663 in Berlin with 24 horses. According to later calculations, to overcome the effort, it was necessary to harness 13 strong draft horses on each side.

Drawing by Gaspard Schott "Magdeburg Hemispheres".

The experiment with the Magdeburg hemispheres proved the existence of atmospheric pressure and is still taught in general physics courses around the world. The original hemispheres and the pump are kept in the Deutsches Museum in Munich. Developing this theme, in 1660 Guericke built the first water barometer and used it for meteorological observations, invented a hygrometer, designed an air thermometer, and a manometer.

The scope of Guericke's interests, however, was not limited to this branch of physics. In 1660, he created one of the first electrostatic machines - a ball of sulfur the size of a medium-sized ball, mounted on an iron axle. By rotating the ball and rubbing it with his palms, Guericke received electricity. With the help of this device, he studied electrical phenomena: he discovered electrostatic repulsion, electric glow (an electrified sulfur ball glowed in the dark).

Numerous physical experiments during his lifetime brought recognition to the scientist and the respectful nickname of the German Galileo. Being engaged in astronomy, he expressed the opinion that comets can return. Guericke also established the elasticity and weight of air, its ability to sustain combustion and respiration, and conduct sound. Proved the presence of water vapor in the air. In 1666, he was the first among scientists to be awarded the title of nobility and became known as Otto von Guericke. The scientist died in Hamburg on May 11, 1686.

The experience with the Magdeburg hemispheres impressed contemporaries so much that the Dukes of Brunswick-Wolfenbüttel used his image on commemorative thalers of 1702 as an allegory. Ruled jointly since 1685, the two duke brothers quarreled. Anton Ulrich was jealous of his wife Elisabeth Juliana of Holstein-Norburg for Rudolf August, which led to their break. In March 1702, Anton Ulrich was removed from power and fled to Saxe-Gotha. On this occasion, the so-called "Luftpumpenthaler" was released - a thaler with an air pump. Its obverse depicts two horses tearing the Magdeburg hemispheres in vain. The interlocked hemispheres are a symbol of the inseparable union of the two Brunswick rulers. On the reverse, without any effort, the two hemispheres fall apart, because a woman's hand opened a valve on them, and air got inside. The engraver illustrated the palace squabble with the help of physical instruments. After the death of Rudolf August in 1704, Anton Ulrich returned to rule.

Braunschweig-Wolfenbüttel. Rudolf August and Anton Ulrich, 1685-1704. Luftpumpenthaler, 1702, Goslar. In honor of fraternal unity. 29.36 Obverse: two horses vainly tearing the Magdeburg hemispheres with the abbreviation RAV, behind them the symbol of chastity a unicorn and an eagle with lightning in its paws, the inscription QVOD VI NON POTVIT (which they could not force). Reverse: on a pedestal two open hemispheres and a woman's hand opening a valve, above a ribbon with the text DISIECTVM EST ARTE MINISTRA (artificially scattered).

Braunschweig-Wolfenbüttel. Rudolf August and Anton Ulrich, 1685-1704. Luftpumpenthaler, 1702, Goslar. In honor of fraternal unity. Obverse: two horses vainly tear apart the Magdeburg hemispheres with the abbreviation RAV, behind them a unicorn and lightnings beating from a cloud, the inscription NON VI (not by violence). Reverse: on a pedestal two open hemispheres and a woman's hand opening a valve, above a ribbon with the text SED ARTE (but art).

On the occasion of the 375th anniversary of the birth of Otto von Guericke, a 10 mark commemorative coin was minted in the GDR.

GDR. 10 stamps, 1977. 375th anniversary of the birth of Otto von Guericke. Ag 500; 31 mm; 17. Circulation: 49,434 pieces.

GDR. 10 stamps, 1977. 375th anniversary of the birth of Otto von Guericke. With the inscription "Test". Ag 500; 31 mm; 17. Circulation: 6,000 pieces.

On the 250th anniversary of the death of Otto von Guericke in the Third Reich, a commemorative medal was minted and a postage stamp was issued.

Bronze medal, 1936. 250th anniversary of the death of Otto von Guericke. 97 mm. Engraver: Rudolf Bosselt (1874-1938). Obverse: bust of Guerike; reverse: coat of arms of Magdeburg and the inscription "Ehrengabe der Stadt Magdeburg" (Honorary gift of the city of Magdeburg).

Third Reich. Postage stamp, 1936. 250th anniversary of the death of Otto von Guericke.

Postage stamps dedicated to Otto von Guerick and his invention were also issued in the GDR and the FRG.

GDR. Postage stamp, 1969. Experience with the Magdeburg hemispheres.

GDR. Postage stamp, 1977. 375th birthday of Otto von Guericke.

Germany. Postage stamp, 2002. 400th anniversary of the birth of Otto von Guericke.

Otto von Guericke(German Otto von Guericke; 1602, Magdeburg - 1686, Hamburg) - German physicist, engineer and philosopher.

He studied law, mathematics and mechanics in Leipzig, Jena and Leiden. For some time he served as an engineer in Sweden. From 1646 he was burgomaster of Magdeburg. In 1650, he invented vacuum pumping and applied his invention to study the properties of vacuum and the role of air in the combustion process and for human breathing. In 1654 he conducted a famous experiment with the Magdeburg hemispheres, which proved the presence of air pressure; established the elasticity and weight of air, the ability to sustain combustion, to conduct sound.

In 1657, he invented a water barometer, with the help of which in 1660 he predicted an impending storm 2 hours before its appearance, thus going down in history as one of the first meteorologists.

In 1663, he invented one of the first electrostatic generators that produced electricity by friction - a ball of sulfur rubbed by hand. In 1672, he discovered that a charged ball crackles and glows in the dark (he was the first to observe electroluminescence). In addition, he discovered the property of electrical repulsion of unipolarly charged objects.

Biography

Otto von Guericke was born into a family of wealthy citizens of Magdeburg. In 1617 he entered the Faculty of Liberal Arts at the University of Leipzig, but in 1619, due to the outbreak of the Thirty Years' War, he was forced to transfer to Helmstedt University, where he studied for several weeks. Then from 1621 to 1623 he studied jurisprudence at the University of Jena, and from 1623 to 1624 he studied the exact sciences and fortification art at the University of Leiden. He completed his studies with a nine-month educational trip to England and France. In November 1625 he returned to Magdeburg, and the following year he married Margarita Alemann and was elected to the collegiate council of the city magistrate, of which he remained a member until old age. As an official, he was responsible for the construction, and in 1629 and 1630-1631 - also for the defense of the city.

Although Guericke himself did not share the sympathy of the inhabitants of Magdeburg with the Swedish Protestant king Gustav II Adolf, when in May the troops of the Catholic League led by Johann Tserklas Tilly stormed and destroyed the city, he lost his property and, almost dying, was captured near Fermersleben. From there, thanks to the mediation of Prince Ludwig of Anhalt-Köthen, he was redeemed for three hundred thalers. Having moved with his family to Erfurt, Guericke became a fortification engineer in the service of Gustav II Adolf (he was in office until 1636).

In February 1632, the entire Guericke family returned to Magdeburg. For the next ten years, von Guericke carried out the restoration of the city, destroyed by fire in 1631. He also rebuilt his own house. Under the Swedish, and from 1636 - the Saxon authorities, he took part in the public affairs of Magdeburg. In 1641 he became the city treasurer, and in 1646 - burgomaster. He held this position for thirty years. In September 1642, Guericke began a rather dangerous and slippery diplomatic activity (continued until 1663), going to the court of the Saxon elector in Dresden in order to achieve an easing of the harsh Saxon military regime in Magdeburg. He took part, in particular, in the conclusion of the Peace of Westphalia, in the work of the deCongress for the execution of peace in Nuremberg (1649-1650) and in the dissolution of the deRegensburg Reichstag (1653-1654). Guericke's scientific and diplomatic interests coincided at this dissolution. Upon invitation, he showed several of his experiments to the highest dignitaries of the Holy Roman Empire, one of whom, Archbishop de Johann Philipp von Schonborn, bought one of Guericke's apparatus and sent it to the Jesuit Collegium in Würzburg. The professor of philosophy and mathematics of this institution, Caspar Schott, became interested in the novelty and from 1656 began to correspond regularly with Otto von Guericke. As a result, he first published his scientific work in an appendix to Schott's Mechanica Hydraulico-pneumatica, published in 1657. In 1664, Schott published the book Techica curiosa in Würzburg, which contained information about Guericke's experiments. A year before, Guericke himself had prepared for publication the manuscript of his fundamental work, Experimenta Nova (ut vocantur) Magdeburgica de Vacuo Spatio, but it was published in 1672 in Amsterdam.