Astrology of love and horoscopes 

What is Planck's quantum theory.  Planck's quantum hypothesis. See what the "Planck Hypothesis" is in other dictionaries

(in portions). Each such portion-quantum has energy , proportional to the frequency ν radiation:

where h or - the coefficient of proportionality, later called Planck's constant. Based on this hypothesis, he proposed a theoretical derivation of the relationship between the temperature of a body and the radiation emitted by this body - Planck's formula.

Planck's hypothesis was later confirmed experimentally.

The advancement of this hypothesis is considered the moment of the birth of quantum mechanics.

see also


Wikimedia Foundation. 2010 .

See what the "Planck Hypothesis" is in other dictionaries:

    Planck's hypothesis

    Philosophical Encyclopedia

    hypothesis- HYPOTHESIS (from the Greek. hypothesis basis, assumption) a special kind of knowledge, as well as a special process of knowledge development. G. in the first sense of the word is a reasonable (not completely) assumption about the causes of the phenomenon, about unobservable connections between ... ... Encyclopedia of Epistemology and Philosophy of Science

    H, one of the universal numerical constants of nature, which is included in many formulas and physical laws that describe the behavior of matter and energy on a microscopic scale. The existence of this constant was established in 1900 by a professor of physics at the Berlin ... Collier Encyclopedia

    - (from the Greek hipothesis basis, assumption) a position put forward as a preliminary, conditional explanation of a certain phenomenon or group of phenomena; assumption about the existence of some phenomenon. G. may concern existence ... ... Glossary of Logic Terms

    This article is about the German physicist. For other uses of the term in the title of the article, see Planck (disambiguation). Max Planck Max Planck ... Wikipedia

    Quantum mechanics ... Wikipedia

    - (from the Greek antinomia contradiction in law) reasoning proving that two statements, which are the negation of each other, follow one from the other. A characteristic example of logical A. is the "Liar" paradox. The most famous of ... ... Philosophical Encyclopedia

    Plancksche Hypothesis- Planko hipotezė statusas T sritis fizika atitikmenys: engl. Planck's hypothesis vok. Plancksche Hypothese, f rus. Planck's hypothesis, f pranc. hypothese de Planck, f … Fizikos terminų žodynas

Books

  • Invectives Against the Law of Entropy Increasing, Strengthened by the Hypothesis of the Universe's Fractality, Khaitun SD. The author's doubts about the validity of the law of entropy growth are due to three considerations. 1. Verification of this law based on the results of tracking the level of complexity of real systems ...

The revolution in physics coincided with the beginning of the 20th century. By the end of the 19th century, scientists believed that the construction of a physical picture of the world was practically completed, and the next generations of scientists would only have to clarify the numbers after the decimal points in physical constants.

Lord Kelvin(Fig. 1): “There is a clear sky above physics, all the laws of physics have already been discovered, only two clouds remain.”

Rice. 1. Lord Kelvin

Kelvin considered the first such cloud to be the propagation of electromagnetic waves in a vacuum at a constant speed without any medium. Einstein's theory of relativity appeared five years later. This theory forced to change the idea of ​​space and time in which we live.

The second cloud, according to Kelvin, is the radiation spectrum of heated bodies. If the body has a high temperature, then it can become a source of visible radiation. The difficulty was that theoretical physics could not explain the radiation spectrum of a heated body. At the beginning of the twentieth century, this difficulty was overcome, the thermal radiation of heated bodies received its own explanation, from this explanation a new field of physics appeared - quantum mechanics.

English scientists Rayleigh and Jeans made an attempt to combine the laws of thermal radiation into one. This law confirmed the experimental data very well, but it corresponded only to the middle part of the emission spectrum for yellow and green rays. When there was a shift towards blue, violet and ultraviolet rays, this law was violated.

From the Rayleigh-Jeans law, it followed that the shorter the wavelength, the greater should be the intensity of thermal radiation(Fig. 2). Nothing like this has been observed experimentally. And in the transition to short waves, the intensity should have grown and is completely unlimited, but this does not happen.

Rice. 2. Rayleigh-Jeans law

No, and there can be no unlimited increase in the intensity of the waves. If any physical law leads to the word "unlimited" - this is its collapse.

Physicists called this situation ultraviolet catastrophe.

At the end of the 19th century, physicists could not assume that this was not a catastrophe of a particular law of radiation, but a catastrophe of a section of classical physics.

Since 1896, Max Planck (Fig. 3) became interested in the problems of thermal radiation from bodies. Any body containing heat emits electromagnetic radiation. If the body is hot enough, then this radiation becomes visible.

Rice. 3. Max Planck

As the temperature rises, the body becomes red hot, then orange-yellow, and finally white (Fig. 4-6).

Rice. 4. Chromaticity of black-body radiation

Rice. 5. Chromaticity of black-body radiation

Rice. 6. Chromaticity of black-body radiation

Maxwell's repeatedly tested laws of electromagnetism do not apply to short waves. This is surprising, since these laws perfectly describe the propagation of radio waves by an antenna.

It was on the basis of these laws that the existence of electromagnetic waves was predicted.

Maxwell's electrodynamics led to a meaningless conclusion: a heated body as a result of constant radiation of electromagnetic waves should have cooled to zero.

From the point of view of classical physics, thermal equilibrium between matter and radiation cannot exist. It has been experimentally proven that a heated body does not spend all its energy on the radiation of electromagnetic waves.

In 1900, Max Planck proposed the quantum hypothesis.

Planck's hypothesis:

A heated body emits and absorbs light not continuously, but in certain finite portions of energy - quanta (quantum (from lat. quantum) - quantity).

The energy of each portion is directly proportional to the radiation frequency.

universal plank (h ) is a constant universal value.

The energy of quanta of different colors has different values ​​(Fig. 7).

For example:

Rice. 7. Energy of quanta

The energy of the light flux is determined by the frequency of radiation and the number of quanta in the flux.

The new theory explained the experimental data.

Max Planck's formula makes it possible to determine various characteristics of electromagnetic study quanta.

Let's solve the problem (Fig. 8–10):

Rice. 8. Task 1

The maximum wavelength of the visible part of the light corresponds to the red color (760 nm).

Rice. 9. Solution of problem 1

Substituting the numbers into the formula, we get the result:

Rice. 10. Solution of problem 1

Let's solve one more problem (Fig. 11–12):

Rice. 11. Task 2

Rice. 12. Solution of problem 2

To determine the type to which radiation should be attributed, you need an electromagnetic scale (Fig. 13):

Rice. 13. Electromagnetic scale

Problem Answer: X-rays.

After Planck's discovery, a new and most modern physical theory began to develop - quantum theory. Its development continues to this day.

3. Development of Planck's hypothesis. Quantum of action

When constructing his theory of equilibrium thermal radiation, Planck proceeded from the assumption that matter is a collection of electronic oscillators, through which energy is exchanged between matter and radiation. Such an oscillator is a material point held near its equilibrium position by force. The magnitude of this force increases in proportion to the deviation from the equilibrium position, and the oscillator is a mechanical system characterized by one peculiar property. This property lies in the fact that the oscillation frequency of the oscillator does not depend on the magnitude of its amplitude.

Following Planck, we define the energy quantum of an oscillator as a quantity equal to the product of the frequency of this oscillator and a constant h, and suppose that when an oscillator interacts with radiation, it can lose or gain energy only in a jump, and the magnitude of this jump is equal to the corresponding energy quantum. But in this form, the energy quantization hypothesis turns out to be applicable only in the case of harmonic oscillators. Indeed, in the general case of a system whose oscillation frequency is not constant, but depends on the oscillation amplitude, the introduced definition of an energy quantum becomes ambiguous. Planck understood the need to give a more general formulation of the principle of quantization, applicable to any mechanical systems and coinciding in the particular case of a harmonic oscillator with the one given above. He reasoned as follows. Since the constant has the dimension of action, i.e., the dimension of the product of energy and time or momentum per path, it can be regarded as an elementary quantity of action, a kind of unit of action in the atomic world. Let us now consider a mechanical system that performs periodic motion and is characterized by only one variable, say, a system consisting of one particle that performs periodic motion along some straight line. For such a system, one can calculate the action integral according to Maupertuis, which coincides with the action integral, which appears in the principle of least action, taken over the full period of motion.

This value is a certain characteristic of periodic motion. Requiring that it be equal to the product of an integer and Planck's constant, we obtain a new formulation of the quantization principle applicable to any one-dimensional periodic motion. It is easy to see that in the special case of a harmonic oscillator this new principle is completely equivalent to the previous principle of energy quantization. In order to give the quantization principle a more general form, Planck had to abandon the original energy quantization hypothesis and replace it with the action quantization hypothesis.

The fact that in the general formulation of the principle of quantization it is action that appears was both natural and somewhat strange. Natural because this quantity plays an essential role in all analytical mechanics according to Hamilton's principle and the principle of least action. This, in turn, led to the fact that the entire apparatus of analytical mechanics, as it were, was already ready to accept the new principle of quantization. The quantization of the action itself seemed strange because from a purely physical point of view it was difficult to understand how such a quantity as action, which is rather abstract in nature and does not directly satisfy any conservation laws, can represent a characteristic of the discreteness of the processes of the atomic world.

The action is always expressed as the product of certain quantities of a geometric nature by the corresponding quantities of a dynamic nature. Pairs of these quantities form canonically conjugate variables in analytical mechanics. Thus, the integral that appears in the Maupertuis principle of least action is a curvilinear integral of the momentum along the trajectory. And a kind of discrete action, expressed by the introduction of Planck's constant, indicates the presence of a certain relationship between space and time, on the one hand, and dynamic phenomena that we are trying to localize in this space and time, on the other. This interrelation has a completely new character, absolutely alien to the concepts of classical physics. And therein lies the profound and revolutionary significance of the ideas that Planck laid at the basis of the theory of equilibrium radiation of a black body.

Planck proceeded from the assumption that matter can emit radiation not continuously, but only in separate finite portions. This, however, does not entail an unambiguous assumption about the discreteness of the radiation structure. Two different theories can be constructed, based on two opposite assumptions regarding the nature of the absorption of radiation by matter. The first, perhaps more consistent and subsequently universally recognized, is based on the assumption that the elements of matter, such as electronic oscillators, can only be in such states of motion that correspond to quantized values ​​of energy. It directly follows from this that both emission and absorption of radiation can occur only in discrete portions, or quanta. This, in turn, necessarily entails the assertion that the radiation structure is discrete.

Confused by this incomprehensible consequence of his own ideas, Planck for a long time tried to develop another, less radical form of quantum theory, in which only the emission of radiation was discrete, and the absorption remained continuous. It was believed that matter can continuously absorb radiation incident on it, but it can only emit it discretely, in separate quanta. It is easy to understand the goal that Planck pursued. He tried to defend and preserve the previous idea of ​​the continuous nature of radiation, since it seemed that only in this case would the quantum theory not contradict the wave theory, which had been repeatedly confirmed in numerous and very precise experiments.

However, for all the ingenuity that Planck put into developing this form of quantum theory, it was refuted by later developments in physics and, in particular, by Einstein's explanation of the photoelectric effect and by the success of Bohr's theory of the atom.

From the book Revolution in Physics author de Broglie Louis

5. The principle of least action Equations of the dynamics of a material point in the field of forces with potential can be obtained based on the principle, which in general terms is called the Hamilton principle, or the principle of stationary action. According to this principle, of all

From the book Lightning and Thunder author Stekolnikov, I S

2. The theory of black body radiation. Planck's quantum of action The beginning of the development of quantum theory was laid by Max Planck's work on the theory of black-body radiation dating back to 1900. An attempt to build a theory of black body radiation based on the laws of classical physics led to

From the book Interestingly about cosmogony author Tomilin Anatoly Nikolaevich

From the book Movement. Heat author Kitaygorodsky Alexander Isaakovich

III. Actions produced by lightning 1. How often does lightning occur? Thunderstorms do not occur equally everywhere on earth. In some hot, tropical places, thunderstorms occur all year round - almost every day. In other places located in the northern regions, thunderstorms occur

From the book History of the Laser author Bertolotti Mario

The Fall of the Nebular Hypothesis The Beginning of the Assault Remember that P. Laplace's reasoning began with a list of features of the solar system. Then he built a hypothesis that best, as it seemed to him, explained all these features. But it was with them that they began

From the book Who Invented Modern Physics? From Galileo's pendulum to quantum gravity author Gorelik Gennady Efimovich

The Last Push and the Collapse of the Nebular Hypothesis By 1900, so many contradictions had accumulated in Laplace's nebular hypothesis that it became obvious that it was time to replace it! However, for its final fall, a push was needed. What was needed was a fact that, being everything

From the book The Atomic Problem by Ren Philip

Hypotheses, hypotheses, hypotheses... K. Weizsacker's hypothesis. The year 1943 began very unfortunately for the Nazis of the Reich: “The Russians are still on the defensive,” they said at the headquarters. But gentlemen, the generals knew that the Soviet troops were not only defending themselves. "Destroyed", according to conviction

From book 6. Electrodynamics author Feynman Richard Phillips

Efficiency Factor With the help of various machines, you can make energy sources do different work - lift loads, move machines, transport goods and people. You can calculate the amount of energy invested in the machine and the value received from it

From the book Quantum. Einstein, Bohr and the great controversy about the nature of reality by Kumar Manjit

Planck's Law The theoretical situation is described as follows. When X. Rubens and his wife visited Planck on Sunday, October 7, 1900, he told Planck about the measurements at wavelengths up to 50 microns, which he had made together with F. Kurlbaum at the Berlin Institute. These

From the author's book

Recognition of Bohr's Hypothesis We may ask how Bohr's theory came about. Rutherford, to whom Bohr sent his manuscript for publication, submitted it to the prestigious English Philosophical Magazine. It suggested that he supported her, even though when Bor

From the author's book

From the author's book

Alpha, Beta, Gamow and the "New Crisis of Quantum Theory" The Jazz Band essentially broke up in 1928 when a black cat ran between two Musketeers and the third - Georgy Gamow - went to Europe. He entered the university before his friends, graduated earlier and went to

From the author's book

Chapter II The Principle of Operation of Nuclear Bombs Having recalled some general information from the field of nuclear physics, we can proceed to a presentation of the principle of operation of nuclear bombs. All nuclear bombs are divided into two large groups: bombs based on the fission reaction, sometimes called

From the author's book

II. Protection against the damaging effects of nuclear bombs 1. Protection against light radiation. The most reliable protection against light radiation is not to be taken by surprise by a flash. We have already said that light radiation propagates in a straight line and

From the author's book

CHAPTER 19 THE LASTEST ACTION PRINCIPLE Post Lecture Addendum When I was in school, our physics teacher, named Bader, once called me over after class and said, “You look like you're terribly tired of everything; listen to something interesting

From the author's book

PART I. Quantum In short, what I did can only be described as an act of desperation. Max Planck There was a feeling that the earth was slipping from under my feet, there was nowhere to see what I could lean on, on which I could build something .Albert Einstein

Physics is the most mysterious of all sciences. Physics gives us an understanding of the world around us. The laws of physics are absolute and apply to everyone without exception, regardless of person and social status.

This article is intended for persons over 18 years of age.

Are you over 18 already?

Fundamental discoveries in quantum physics

Isaac Newton, Nikola Tesla, Albert Einstein and many others are the great guides of mankind in the wonderful world of physics, who, like prophets, revealed to mankind the greatest secrets of the universe and the ability to control physical phenomena. Their bright heads cut through the darkness of ignorance of the unreasonable majority and, like a guiding star, showed the way to humanity in the darkness of the night. One of these conductors in the world of physics was Max Planck, the father of quantum physics.

Max Planck is not only the founder of quantum physics, but also the author of the world famous quantum theory. Quantum theory is the most important component of quantum physics. In simple terms, this theory describes the movement, behavior and interaction of microparticles. The founder of quantum physics also brought us many other scientific works that have become the cornerstones of modern physics:

  • theory of thermal radiation;
  • special theory of relativity;
  • research in the field of thermodynamics;
  • research in the field of optics.

The theory of quantum physics about the behavior and interaction of microparticles became the basis for condensed matter physics, elementary particle physics and high energy physics. Quantum theory explains to us the essence of many phenomena of our world - from the functioning of electronic computers to the structure and behavior of celestial bodies. Max Planck, the creator of this theory, thanks to his discovery allowed us to comprehend the true essence of many things at the level of elementary particles. But the creation of this theory is far from the only merit of the scientist. He was the first to discover the fundamental law of the universe - the law of conservation of energy. The contribution to science of Max Planck is difficult to overestimate. In short, his discoveries are priceless for physics, chemistry, history, methodology and philosophy.

quantum field theory

In a nutshell, quantum field theory is a theory of the description of microparticles, as well as their behavior in space, interaction with each other and mutual transformations. This theory studies the behavior of quantum systems within the so-called degrees of freedom. This beautiful and romantic name says nothing to many of us. For dummies, degrees of freedom are the number of independent coordinates that are needed to indicate the motion of a mechanical system. In simple terms, degrees of freedom are characteristics of motion. Interesting discoveries in the field of interaction of elementary particles were made by Steven Weinberg. He discovered the so-called neutral current - the principle of interaction between quarks and leptons, for which he received the Nobel Prize in 1979.

The Quantum Theory of Max Planck

In the nineties of the eighteenth century, the German physicist Max Planck took up the study of thermal radiation and eventually received a formula for the distribution of energy. The quantum hypothesis, which was born in the course of these studies, marked the beginning of quantum physics, as well as quantum field theory, discovered in the 1900th year. Planck's quantum theory is that during thermal radiation, the energy produced is emitted and absorbed not constantly, but episodically, quantumly. The year 1900, thanks to this discovery made by Max Planck, became the year of the birth of quantum mechanics. It is also worth mentioning Planck's formula. In short, its essence is as follows - it is based on the ratio of body temperature and its radiation.

Quantum-mechanical theory of the structure of the atom

The quantum mechanical theory of the structure of the atom is one of the basic theories of concepts in quantum physics, and indeed in physics in general. This theory allows us to understand the structure of everything material and opens the veil of secrecy over what things actually consist of. And the conclusions based on this theory are very unexpected. Consider the structure of the atom briefly. So what is an atom really made of? An atom consists of a nucleus and a cloud of electrons. The basis of the atom, its nucleus, contains almost the entire mass of the atom itself - more than 99 percent. The nucleus always has a positive charge, and it determines the chemical element of which the atom is a part. The most interesting thing about the nucleus of an atom is that it contains almost the entire mass of the atom, but at the same time it occupies only one ten-thousandth of its volume. What follows from this? And the conclusion is very unexpected. This means that the dense matter in the atom is only one ten-thousandth. And what about everything else? Everything else in the atom is an electron cloud.

The electron cloud is not a permanent and even, in fact, not a material substance. An electron cloud is just the probability of electrons appearing in an atom. That is, the nucleus occupies only one ten thousandth in the atom, and everything else is emptiness. And if we take into account that all the objects around us, from dust particles to celestial bodies, planets and stars, are made of atoms, it turns out that everything material is actually more than 99 percent of emptiness. This theory seems completely unbelievable, and its author, at least, a delusional person, because the things that exist around have a solid consistency, have weight and can be felt. How can it consist of emptiness? Has a mistake crept into this theory of the structure of matter? But there is no error here.

All material things appear dense only due to the interaction between atoms. Things have a solid and dense consistency only due to attraction or repulsion between atoms. This ensures the density and hardness of the crystal lattice of chemicals, of which everything material consists. But, an interesting point, when, for example, the temperature conditions of the environment change, the bonds between atoms, that is, their attraction and repulsion, can weaken, which leads to a weakening of the crystal lattice and even to its destruction. This explains the change in the physical properties of substances when heated. For example, when iron is heated, it becomes liquid and can be shaped into any shape. And when ice melts, the destruction of the crystal lattice leads to a change in the state of matter, and it turns from solid to liquid. These are clear examples of the weakening of bonds between atoms and, as a result, the weakening or destruction of the crystal lattice, and allow the substance to become amorphous. And the reason for such mysterious metamorphoses is precisely that substances consist of dense matter only by one ten-thousandth, and everything else is emptiness.

And substances seem to be solid only because of the strong bonds between atoms, with the weakening of which, the substance changes. Thus, the quantum theory of the structure of the atom allows us to take a completely different look at the world around us.

The founder of the theory of the atom, Niels Bohr, put forward an interesting concept that the electrons in the atom do not radiate energy constantly, but only at the moment of transition between the trajectories of their movement. Bohr's theory helped explain many intra-atomic processes, and also made a breakthrough in the science of chemistry, explaining the boundary of the table created by Mendeleev. According to , the last element that can exist in time and space has the serial number one hundred thirty-seven, and elements starting from one hundred and thirty-eighth cannot exist, since their existence contradicts the theory of relativity. Also, Bohr's theory explained the nature of such a physical phenomenon as atomic spectra.

These are the interaction spectra of free atoms that arise when energy is emitted between them. Such phenomena are typical for gaseous, vaporous substances and substances in the plasma state. Thus, quantum theory made a revolution in the world of physics and allowed scientists to advance not only in the field of this science, but also in the field of many related sciences: chemistry, thermodynamics, optics and philosophy. And also allowed humanity to penetrate the secrets of the nature of things.

There is still a lot to be done by humanity in its consciousness in order to realize the nature of atoms, to understand the principles of their behavior and interaction. Having understood this, we will be able to understand the nature of the world around us, because everything that surrounds us, starting with dust particles and ending with the sun itself, and we ourselves - everything consists of atoms, the nature of which is mysterious and amazing and fraught with a lot of secrets.

In physics, not all phenomena and objects are observed directly. For example, an electric field. What we observe is the interaction of bodies, and by the interaction of bodies we judge the electric charge, the electric field that is created around it. If we cannot observe something directly, we can judge it by its manifestations.

We also do not see a beam of light until something hits it: a midge, smoke, a wall (see Fig. 1).

Rice. 1. Midge in the path of a beam of light

Compare how you see sunlight in a room with clean air - only in the form of sunbeams on the floor and furniture (see Fig. 2) (the fact that air molecules come across in the path of the beam is difficult to notice with the naked eye), and in a dusty room - in the form of explicit rays (see Fig. 3).

Rice. 2. Light in a clean room

Rice. 3. Light in a dusty room

When studying light by its interaction with matter, its very interesting property was discovered: light energy is emitted and absorbed in portions, which are called quanta. Unusual to hear? But in nature, this property is not so rare, we do not even notice it. This is what we will talk about today.

There are things that we can count in pieces, like fingers on a hand, pens on a table, cars ... There is one car, but there are two, there can be no average, half a car is already a pile of spare parts. Now, pencils, cars, all things that are separate and that we can count are discrete. Unlike them, try to count the water: one, two ... Water is continuous, it can be poured in a stream, which can always be interrupted (see Fig. 4).

Rice. 4. Water is continuous

Is sugar continuous? At first glance, yes. It, like water, can be taken with a spoon as much as you like. What if you look closer? Sugar consists of grains of sand, which we can count (see Fig. 5).

Rice. 5. Sugar crystals

It turns out that if there is a lot of sugar in the sugar bowl and we take it from there with a spoon, we are not interested in individual crystals and we consider it continuous. But for an ant that carries one or two crystals, and for us, watching it through a magnifying glass, sugar is discrete. The choice of model depends on the problem being solved. You understand well what discreteness and continuity are when you buy some products by the piece, and others by weight.

If you look even closer, you can also consider water as discrete: for a long time you will not surprise anyone with the fact that substances consist of individual atoms and molecules. And it is also impossible to take half a molecule of water (see Fig. 6).

Rice. 6. Close view of the water

We know the same about electric charge: the charge of a body can only take values ​​that are multiples of the charge of an electron or a proton, because these are elementary charge carriers (see Fig. 7).

Rice. 7. Elementary charge carriers

Everything continuous at some level of study becomes discrete, the only question is at what level.

Examples of discreteness in nature

Look at the species diversity of the living world: there is a hippopotamus with a short neck and there is a giraffe with a long one. But there are not many intermediate forms among which one could find an animal with any neck length. It is clear that there are other animals with all kinds of necks, but the length of the neck is only one sign. If we take a set of features, then each species has its own set, and again there is no set of intermediate forms with all intermediate features (see Fig. 8).

Rice. 8. A set of signs of animals

Animals, like plants, come in separate distinct species. The key word is individual, that is, wildlife in its species diversity is discrete.

Heredity is also discrete: traits are transmitted by genes, and there cannot be half a gene: it either exists or it does not. Of course, there are many genes, so the traits they code for seem to be continuous, like sugar in a big bag. We do not see people in the form of constructors assembled from a set of templates: one of three standard hair colors, one of five eye colors (see Fig. 9).

Rice. 9. A person is not assembled like a constructor from a set of features.

In addition, the body, in addition to heredity, is influenced by environmental conditions.

Discreteness is also visible in resonant frequencies: lightly hit a glass standing on the table. You will hear a ringing: the sound of a certain - resonant for this glass - frequency. If the blow is strong enough and the glass staggers, then it will also stagger with a certain frequency (see Fig. 10).

Rice. 10. Strong blow to the glass

If it is with water, circles will go along it, the surface of the water will oscillate with a frequency that is resonant for this water in a glass (see Fig. 11).

Rice. 11. Full glass of water

In this system, in our example it was a glass of water, the oscillations do not occur at any frequency, but only at certain ones - again discreteness.

Even water, while it flows from the tap in a trickle, we consider continuous, and when it starts to drip - discrete. Yes, we do not think that drops are indivisible, like molecules, but we consider them individually, we are not talking about the rate of water outflow, for example, 2 ml per second, if one drop falls, for example, in 5 seconds. That is, we apply a model of water consisting of drops.

Prior to this, discreteness, or quantization, was noticed in matter. Max Planck was the first to point out that energy also has this property. Planck suggested that the energy of light is discrete, and one portion of energy is proportional to the frequency of light. He did this when solving the problem of thermal radiation. We do not have enough knowledge to understand this problem, but Planck solved it, and most importantly, his assumption was confirmed experimentally.

Planck's hypothesis is as follows: the energy of vibrating molecules and atoms does not take any, but only certain certain values. This means that during radiation, the energy of radiating molecules and atoms changes in jumps. Accordingly, light is not emitted continuously, but in some portions, which Planck called quanta(see fig. 12).

Rice. 12. Light quanta

Planck's hypothesis was proved by the discovery and explanation of the photoelectric effect: this is the phenomenon of the emission of electrons by a substance under the action of light or other electromagnetic radiation. It happens like this: the energy of one quantum is transferred to one electron (see Fig. 13).

Rice. 13. Quantum energy is transferred to one electron

It goes to tear the electron out of the substance, and the remaining energy goes to accelerate the electron, goes into its kinetic energy. And here's what they noticed: the higher the frequency of light, the faster the electrons accelerate. This means that the energy of one radiation quantum is proportional to the radiation frequency. Planck accepted:

where E is the radiation quantum energy in joules, ν is the radiation frequency in hertz. Obtained by matching the experimental data with the theory, the coefficient of proportionality is equal to , was named Planck's constant.

It is surprising that we say: “light exhibits the properties of a stream of particles”, and we associate the energy of these particles with frequency - a characteristic of a wave, not a particle. That is, we do not say that light is a stream of particles, we simply apply the model, if only it would help us describe the phenomenon.

Photoelectric effect. Einstein's equation for the photoelectric effect

The phenomenon of the photoelectric effect has become a confirmation of the quantum hypothesis, here the quantum model works well.

How a wave can knock an electron out of matter is not clear. And even more so it is not clear why radiation with one frequency knocks out an electron, and with another frequency - no. And how is the radiation energy distributed among the electrons: will the radiation impart more energy to one electron or less energy to two?

Using the quantum model, we can easily understand everything: one absorbed quantum of light energy (photon) can pull out only one photoelectron from a substance (see Fig. 14).

Rice. 14. One photon knocks out one photoelectron

If a quantum of light energy is not enough for this, the electron is not knocked out, but remains in the substance (see Fig. 15).

Rice. 15. Electron remains in matter

Excess energy is transferred to the electron in the form of the kinetic energy of its movement after leaving the substance. And how many such quanta will be, so many electrons will be affected by them.

We will have a separate lesson on the photoelectric effect, and then we will talk about it in more detail, but already now we will understand the Einstein equation for the photoelectric effect (see Fig. 16).

Rice. 16. The phenomenon of the photoelectric effect

It reflects what we have said, and looks like this:

is the work function is the minimum energy that must be imparted to an electron in order for it to leave the metal. This is a characteristic of the metal and the state of its surface.

A quantum of light energy is spent on doing the work function and on communicating kinetic energy to the electron.

The photoelectric effect, and the equation that describes it, was used to derive and test the value of , obtained by Planck. See the next thread for more on this.

Experimental determination of Planck's constant

Using the Einstein equation, you can determine the Planck constant, for this you need to experimentally determine the frequency of light, the work function A, and the kinetic energy of photoelectrons. This was done, and a value was obtained that coincided with that which was theoretically found by Planck when studying a completely different phenomenon - thermal radiation.

In physics, we often come across constants (for example, the Avogadro number, the boiling point of water, the universal gas constant, etc.). Such constants are unequal, among them there are so-called fundamental ones, on which the building of physics is built. Planck's constant is one of these constants, in addition to it, the fundamental constants include the speed of light and the gravitational constant.

One portion of radiation can be considered a particle of light - a photon. The energy of a photon is equal to one quantum. In the formulation of the problems, we will equally use the terms "photon energy" and "quantum of light energy". Also, these properties of light are called corpuscular (corpuscle means particle).

In accordance with Planck's hypothesis, the radiation energy is the sum of the minimum fractions, i.e., the total radiated energy takes on discrete values:

where is a natural number.

Since the size of the minimum portion of energy is , then, for example, a portion (or quantum) of radiation in the red range has a lower energy than a portion (or quantum) of radiation in the ultraviolet range.

Let's solve the following problem.

The radiation power of a laser pointer with a wavelength is . Determine the number of photons emitted by the pointer in 2 s.