Frequent reasons for limiting waves

It would seem that there should be waves of all frequencies ($ \ nu $) from $ \ nu = 0 \ Hz $ to $ \ nu = \ infty \ Hz. $ However, since a light wave has corpuscular properties in addition to wave properties, there are some restrictions ... Quantum theory States that electromagnetic radiation is emitted in the form of quanta (portions of energy). Quantum energy (W) is related to its frequency by the expression:

where $ h = 6.62 \ cdot (10) ^ (- 34) J \ cdot c $ is Planck's constant, $ \ hbar = \ frac (h) (2 \ pi) = 1.05 \ cdot (10) ^ (- 34) J \ cdot c $ - Planck's constant with a bar. From expression (1) it follows that infinite frequencies are impossible, since there are no quanta with infinitely high energy. The same expression imposes restrictions on low frequencies, since there is a minimum value of the energy cable ($ W_0 $), from which it follows that the minimum frequency ($ (\ nu) _0 $) is equal to:

Note 1

I must say that to this day in physics the existence of lower bound energy of photons. The minimum frequency of the order of 8 Hz is observed in standing electromagnetic waves between the ionosphere and the earth's surface.

Scale of electromagnetic waves

All known today electromagnetic waves are divided into:

Picture 1.

Each of the ranges has its own characteristics. With increasing frequency, the manifestation of the corpuscular properties of radiation increases. Waves different parts spectrum by different ways of generation. Each waveband studies its own branch of physics. These parts of the spectrum differ not in their physical nature, but in the way they are received and received. There are no sharp transitions between these types of waves, areas may overlap, boundaries are conditional.

The visible part of the spectrum of electromagnetic waves in conjunction with the zone of ultraviolet and infrared radiation is studied in optics (the so-called optical range). The quanta of radiation in the visible range are called photons. Their energy lies in the interval:

The entire spectrum of electromagnetic radiation has wave and quantum properties, but depending on the wavelength, one type of properties prevails in importance over the other, respectively, different methods of their study are used. Different wavelength groups have different practical uses depending on the wavelength.

Features of different types of electromagnetic radiation

The features of the optical range are:

• compliance with the laws of geometric optics,
• weak interaction of light with matter.

Note 2

For frequencies lower than the optical range, the laws of geometric optics cease to apply, while the electromagnetic field of high frequencies either passes through the substance or destroys it. Visible light is a necessary condition for life on Earth, as it is a prerequisite for photosynthesis.

Radio waves used for radio communication, television, radar. These are the longest waves in the electromagnetic spectrum. It is easy to artificially generate radio waves using an oscillatory circuit (connection of capacitance and inductance). Atoms and molecules are capable of emitting radio waves, which is used in radio astronomy. In the very general view, it should be noted that the emitter of electromagnetic waves are accelerated moving charged particles located in atoms and nuclei.

Infrared Spectrum was first experimentally studied in 1800 by V. Herschel... The scientist placed the thermometer at the red end of the spectrum and recorded a rise in temperature, which meant heating the thermometer with invisible radiation. Infrared radiation is emitted by any heated body. Using special means, infrared radiation can be converted into visible light. This is how images of heated bodies are obtained in the dark. Infrared radiation is used to dry something.

Ultraviolet radiation was discovered by I. Ritter. He discovered that beyond the violet end of the spectrum, there are rays that are invisible to the eye, which affect some chemical compounds... It is capable of killing pathogenic bacteria, which is why it is widely used in medicine. Ultraviolet radiation in the sun's rays affects the human skin, causing it to darken (tan).

X-rays were discovered by W. Roentgen in 1895. They are invisible to the eye, pass without significant absorption through large layers of matter that are opaque to visible light. X-rays are detected by their ability to cause some crystals to glow and affect photographic film. These rays are used in particular in medical diagnostics. X-rays have strong biological effects.

Definition 1

Gamma radiation is the radiation emitted by excited atomic nuclei and interacting elementary particles... This is the shortest wavelength radiation. It has the most pronounced corpuscular properties. Usually gamma radiation is considered as a flux of gamma quanta. In the wavelength region of the order of $ (10) ^ (- 10) - (10) ^ (- 14) m $, the gamma and X-ray ranges overlap.

Example 1

Exercise: What is the emitter for different types electromagnetic waves?

Solution:

Moving charged particles are always the emitter of electromagnetic waves. In atoms and nuclei, these particles move with acceleration, which means they are sources of electromagnetic waves. Atoms and molecules emit radio waves. This is the only type of wave that can be artificially generated using an oscillatory circuit. Infrared radiation is mainly produced by vibrations of atoms in molecules. These vibrations are called thermal, since they are generated by thermal collisions of molecules. As the temperature rises, the vibration frequency increases.

The visible rays are generated by separate excited atoms.

Ultraviolet light is also referred to as atomic light.

X-rays are emitted due to the fact that electrons with high kinetic energy interact with atoms and nuclei of atoms or the nuclei of atoms themselves emit due to their own excitation.

Gamma rays are generated by excited atomic nuclei and arise during the interaction and mutual transformations of elementary particles.

Example 2

Exercise: What are the frequencies of visible wavelengths?

Solution:

The visible range is the collection of waves that the human eye perceives. The boundaries of this range depend on individual characteristics human vision, and is approximately within $ \ lambda = 0.38-0.76 \ micron. $

There are two types of frequencies used in optics. Circular frequency ($ \ omega $), which is defined as:

\ [\ omega = \ frac (2 \ pi) (T) \ left (2.1 \ right), \]

where $ T $ is the period of wave oscillations. Also use the frequency $ \ nu $, which is associated with the oscillation period as:

\ [\ nu = \ frac (1) (T) \ left (2.2 \ right). \]

Therefore, both frequencies are related to each other by the ratio:

\ [\ omega = 2 \ pi \ nu \ left (2.3 \ right). \]

Knowing that the speed of propagation of electromagnetic waves in vacuum is equal to $ c = 3 \ cdot (10) ^ 8 \ frac (m) (c) $, we have:

\ [\ lambda = cT \ to T = \ frac (\ lambda) (c) \ left (2.4 \ right). \]

In this case, for the boundaries of the visible range, we get:

\ [\ nu = \ frac (c) (\ lambda), \ \ omega = 2 \ pi \ frac (c) (\ lambda). \]

Using what we know the wavelengths for visible light, we get:

\ [(\ nu) _1 = \ frac (3 \ cdot (10) ^ 8) (0.38 \ cdot (10) ^ (- 6)) = 7.9 \ cdot (10) ^ (14) \ left (Hz \ right), \ (\ nu) _2 = \ frac (3 \ cdot (10) ^ 8) (0.76 \ cdot (10) ^ (- 6)) = 3.9 \ cdot (10) ^ (14) \ left (Hz \ right). \] \ [(\ Omega) _1 = 2 \ cdot 3.14 \ cdot 7.9 \ cdot (10) ^ (14) = 5 \ cdot (10) ^ ( 15) \ left (c ^ (- 1) \ right), (\ omega) _1 = 2 \ cdot 3.14 \ cdot 3.9 \ cdot (10) ^ (14) = 2.4 \ cdot (10) ^ (15) \ left (c ^ (- 1) \ right). \ \]

Answer: $ 3.9 \ cdot (10) ^ (14) Hz

"Electromagnetic waves and their properties" - Gamma radiation - the shortest wavelength of radiation. Long waves are well diffracted around the spherical surface of the Earth. Ultra-short waves. Medium waves. In 1901, Roentgen was the first physicist to receive Nobel Prize... It is emitted by atoms and molecules of matter. Highest energy radiation.

"Electromagnetic waves lesson" - http://elementy.ru/posters/spectrum. Ultraviolet radiation. Gamma radiation. What type of radiation do electromagnetic waves with a length of 0.1 mm belong to? Indicate the wavelength interval of visible light in a vacuum. Electromagnetic nature. Wavelength. Development of a natural - scientific understanding of the world. 1. Ultraviolet 2. X-ray 3. Infrared 4.? - Radiation.

"Transformer" - 17. 8. I1, I2 - current in the primary and secondary windings. Remember what and how the EMF of induction in the coil depends. When does the transformer increase the voltage? 1. P2 =. The law of electromagnetic induction. 15.

"Electromagnetic radiation" - An egg under radiation. Recommendations: Reduce the time of communication on a mobile phone. Study of electromagnetic radiation cell phone... The influence of electromagnetic waves on a living organism. Bloodworm, which was under radiation for two days mobile phone... "Investigation of the electromagnetic radiation of a cell phone."

"Electromagnetic field" - Imagine a conductor through which flows electricity... What is an electromagnetic wave? The speed of electromagnetic waves in matter v is always less than in vacuum: v ‹c. But the charge is at rest only relative to a certain frame of reference. There will be a disturbance in the electromagnetic field. What is the nature of an electromagnetic wave?

"Physics of electromagnetic waves" - What is a magnetic field? EM wave - transverse! Propagation of a linearly polarized electromagnetic wave. EM wave speed: The existence of electromagnetic waves was predicted by M. Faraday in 1832. What is an electromagnetic field? Properties of EM waves: James Clerk Maxwell. Repetition: The presence of acceleration is the main condition for the emission of EM waves.

There are 17 presentations in total

other presentations on types of radiation

"Transformer" - Brainstorming. Find the error in the circuit. Improvement of the transformer. Write down the characteristics of the transformer. N1, N2 - the number of turns of the primary and secondary windings. 7. I1, I2 - amperage in the primary and secondary windings. Transformer. AC power supply. Knowledge update. 4.

"Physics of electromagnetic waves" - Physics lesson in grade 11 teacher - Khatenovskaya E.V. MOU SOSH No. 2, Krasnoe village. What is an electric field? J. Electromagnetic waves - electromagnetic oscillations that propagate in space with a finite speed. James Clerk Maxwell. EM Wave Velocity: Refraction and Reflection. What is an electromagnetic field?

"Electromagnetic waves and their properties" - For example, almost all gamma radiation is absorbed earthly atmosphere... The propagation conditions of ultra-long radio waves are investigated by observing thunderstorms. The ultraviolet range is obscured by X-rays. In 1801, I. Ritter and W. Wolaston discovered ultraviolet radiation. In other ranges, thermocouples and bolometers are used. ...

"Electromagnetic waves lesson" - Author: Saturnova Ya.V., physics teacher, secondary school № 10, Monchegorsk [email protected] Visible light. Electromagnetic nature. 1.Radio radiation 2.X-ray 3.Ultraviolet and X-ray 4.Radioradiation and infrared. Similarities. Gamma radiation. Differences. Development of a natural - scientific understanding of the world.

"Electromagnetic field" - The theory of the electromagnetic field. What is the nature of an electromagnetic wave? An alternating magnetic field will create an alternating electric field. Properties of electromagnetic waves: There will be a disturbance in the electromagnetic field. What will happen next? What is an electromagnetic wave? The existence of electromagnetic waves was predicted by J.

The lengths of electromagnetic waves that can be recorded by instruments are in a very wide range. All these waves have common properties: absorption, reflection, interference, diffraction, dispersion. These properties can, however, manifest themselves in different ways. The sources and receivers of the waves are different.

Radio waves

ν = 10 5 - 10 11 Hz, λ = 10 -3 -10 3 m.

Obtained using oscillatory circuits and macroscopic vibrators. Properties. Radio waves of different frequencies and wavelengths are absorbed and reflected in different ways by the media. Application Radio communication, television, radar. In nature, radio waves are emitted by various extraterrestrial sources (galactic nuclei, quasars).

Infrared radiation (thermal)

ν = 3-10 11 - 4. 10 14 Hz, λ = 8. 10 -7 - 2. 10 -3 m.

It is emitted by atoms and molecules of matter.

Infrared radiation is emitted by all bodies at any temperature.

A person emits electromagnetic waves λ≈9. 10 -6 m.

Properties

1. It passes through some opaque bodies, as well as through rain, haze, snow.
2. Produces a chemical effect on photographic plates.
3. Absorbed by the substance, heats it up.
4. Causes an internal photoelectric effect in germanium.
5. Invisible.

Recorded by thermal methods, photoelectric and photographic.

Application... Images of objects are obtained in the dark, night vision devices (night binoculars), fog. They are used in forensic science, in physiotherapy, in industry for drying painted products, walls of buildings, wood, fruits.

Part of the electromagnetic radiation perceived by the eye (from red to violet):

Properties.V works on the eye.

(less than violet light)

Sources: gas discharge lamps with quartz tubes (quartz lamps).

It is emitted by all solids with T> 1000 ° С, as well as by luminous mercury vapor.

Properties... High chemical activity (decomposition of silver chloride, luminescence of zinc sulfide crystals), invisibly, high penetrating ability, kills microorganisms, in small doses has a beneficial effect on the human body (sunburn), but in large doses it has a negative biological effect: changes in cell development and metabolism substances, effects on the eyes.

X-rays

They are emitted at high acceleration of electrons, for example, their deceleration in metals. Obtained using an X-ray tube: electrons in a vacuum tube (p = 10 -3 -10 -5 Pa) are accelerated by an electric field at high voltage, reaching the anode, and sharply decelerated upon impact. During deceleration, electrons move with acceleration and emit short-wavelength electromagnetic waves (from 100 to 0.01 nm). Properties Interference, X-ray diffraction by crystal lattice, high penetrating power. Exposure to high doses of radiation causes radiation sickness. Application... In medicine (diagnosis of diseases internal organs), in industry (control of the internal structure of various products, welds).

γ-radiation

Sources of: atomic nucleus (nuclear reactions). Properties... Has a huge penetrating power, has a strong biological effect. Application... In medicine, production ( γ -defectoscopy). Application... In medicine, in industry.

A common property of electromagnetic waves is that all radiation has both quantum and wave properties. In this case, quantum and wave properties do not exclude, but complement each other. The wave properties are brighter at low frequencies and less bright at high frequencies. Conversely, quantum properties are more pronounced at high frequencies and less brightly at low frequencies. The shorter the wavelength, the brighter the quantum properties appear, and the longer the wavelength, the brighter the wave properties appear.

Physics lesson in grade 11

"Traveling on the scale of electromagnetic waves"

using design technology and ICT "

Physics teacher of the Municipal Educational Institution "Gatchina Secondary School No. 9 with in-depth study of subjects"

Titova Tatiana Viktorovna

This lesson is held in the 11th grade and is the final one in the sections “Electromagnetic waves”, “Optics”. Lesson time - 2 hours. Students already know the basic properties of electromagnetic waves, the reasons for their occurrence, methods of their generation and registration, the main characteristics of electromagnetic radiation, they know the formulas describing wave processes, they can give examples of the practical application of electromagnetic radiation.

Lesson objectives:

Show the importance of the topic "Spectrum of electromagnetic waves" in the formation of students' ideas about physical picture the world; to clarify the idea of ​​the structure of matter;

Show the capabilities of the computer in the organization of the educational process.

Lesson Objectives:

Educational:

1. generalize, systematize the previously studied material about the entire range of electromagnetic radiation;

   deepen knowledge on this topic;

Developing:

1. improve the intellectual abilities and development of students' speech, form the ability to highlight the main thing, compare, generalize, draw conclusions;

   stimulate interest in the subject by attracting additional material;

   to form the need for deepening and expanding knowledge.

Educational:

1. develop cognitive interest.

Lesson type - repetition and consolidation of previously acquired knowledge, control of students' knowledge and skills.

Overall plan lesson:

Organizing time.

Motivation.

Lesson plan message:

1. Electromagnetic waves;

   The history of the discovery of electromagnetic waves;

   Properties of electromagnetic waves;

   Characteristics and basic properties of electromagnetic waves (general overview of the scale of electromagnetic waves).

Conclusion. Conclusions.

Homework.

Repetition of formulas on the topic "Quantum theory";

Independent work.

Summing up the lesson.

Lesson plan

Lesson stage

Teacher activity

Student activities

organizational

Greetings. Communication of the goal, objectives, lesson plan

Accept goals cognitive activities, preparation for work in the lesson

Organization of information perception. Checking previously studied material

Frontal poll, slide show

Answer from their place, work in a notebook

Repetition of material

View slides, comments on student presentations

Design in the notebook of the table

Pinning the topic. Test.

Slide view, frontal survey

Solving problems at the blackboard, repeating formulas

Summing up the lesson. Independent work. Homework recommendations

Performance test items, comments of the teacher when registering the work.

Completing the assignment.

Answers to questions of reflection. Homework recording.

Organizing time. Message of the topic and purpose of the lesson (slide number 1,2)

Motivation.

Teacher.

In 1862, Maxwell * predicted the existence of electromagnetic waves on the basis of his theory of electromagnetism. From his calculations it followed that the speed of their propagation is equal to the previously measured speed of light in air. This fact unambiguously testified to the electromagnetic nature of light.

The full electromagnetic spectrum covers an infinitely large range of wavelengths. It starts from the longest: with a wavelength of 1.5 · 10 13 cm and ends with the shortest gamma rays of radium with a wavelength of 4.7 · 10 -11 cm.

The longest waves are 3 · 10 23 times longer than the shortest ones (slide №3).

In our daily life, we deal with different types of electromagnetic radiation that are used in science, medicine, i.e. the role of electromagnetic radiation is great, and there is a lot of information about electromagnetic waves.

* Draw the attention of students to the portrait of the scientist on the stand.

Lesson plan message (slide number 4)

Frontal survey (updating knowledge).

Teacher:

What wave is called electromagnetic? (slide number 5.6)

What is the history of electromagnetic waves? (slide number 7.8)

List General characteristics and properties that allow you to combine all types of electromagnetic radiation in the scale of electromagnetic waves (slide number 9).

Students.

The speed of an electromagnetic wave is finite and in a vacuum is equal to the speed of light.

Any accelerating or oscillating charge emits electromagnetic waves.

Around the source of electromagnetic waves, there is a periodic change in the characteristics of the electric and magnetic fields (vectors of intensity and magnetic induction).

The directions of oscillations of the vectors of the intensity of the magnetic induction are mutually perpendicular, and also perpendicular to the direction of wave propagation, which means that electromagnetic waves are transverse.

Electromagnetic waves have the following properties: interference, diffraction, polarization.

Overview of the scale of electromagnetic radiation (slide number 10)

Teacher:

Different ranges of electromagnetic waves have received different names, but one should not forget about general properties such waves: all types of radiation are of the same nature and differ from each other only in their frequencies. If these frequencies are plotted in a certain scale on the axis, then we get a diagram or a scale of waves *.

Traveling along the scale of electromagnetic waves, you will keep records in a special diary - a table (slide number 11). (Appendix # 1).

APPENDIX №1.

TABLE.

Scale of electromagnetic waves.

Spectrum name

Wavelength

physical characteristics

Sources of

Properties

Application

* To draw the attention of students to the scale of electromagnetic waves on the stand.

Students present prepared presentations and mini-performances by wavelength range.

(low frequency vibrations)

Leading number 1.

Electromagnetic waves travel over great distances, so they transmit information, including sound and images.

Presentation by students (slides number 12-19) *

* After each slide, give 1 minute to each student. to write to the table.

1. Solving the problem of applying the ratio of wave motion (slide number 20)

In 1897 the Russian physicist P.N. Lebedev received electromagnetic radiation with a wavelength of 6 mm. Calculate the frequency and period of such waves (the solution to the problem for self-testing is given on slide 21).

(Infrared radiation)

Leading number 2.

Once in distant kingdom a terrible disaster happened. Heavy rains flooded the crop. A terrible famine threatened people. The tsar thought and instructed three heroes to save people from misfortune, and to increase their glory as well. The heroes gathered for the journey. They rode, rode, and around the forest and swamps, ditches and cliffs. What they did not see on their way. And so they drove out into an open field at the crossroads of three roads, where the stone lay. And on that stone there was an inscription: “if you go to the right, you will enter the infrared kingdom; if you go straight, you will find yourself in the ultraviolet principality; if you go to the left, you will enter the kingdom of visible light. " And the good fellows dispersed along three paths: Alyosha Popovich - to the kingdom of visible light, Dobrynya Nikitich - to the ultraviolet principality, and Ilya Muromets - to the infrared kingdom.

Teacher:

Who are we going to follow? We need to get to the IR - kingdom.

Students:

Follow Ilya Muromets to the infrared kingdom!

Lead number 2:

Ilya Muromets walks along the path and does not see anything remarkable, but he feels that the heat is unbearable in this part of the spectrum, and there are no obvious and visible reasons for this!

Ilya Muromets:

Probably, I got into the zone of invisible radiation!

Lead number 2:

Suddenly swooped strong wind, spun the hero and a voice rang out.

Why did you come to my kingdom? You will not leave alive and you will not collect bones until you have solved my three riddles. First question: “Who am I? Where are my relatives from? "

Ilya Muromets:

Most sources of visible light emit, in addition to visible rays, also rays invisible to our eye. These are infrared rays. They are of the same nature as the visible. They are electromagnetic waves, the length of which is 3 · 10 -5 m. Any body, even a human, can be their source. Emitters are atoms and molecules, or rather, electrons and ions (slide 22).

OK! Second question: "What are the properties of my behavior?"

Ilya Muromets:(slides with properties appear along with the answer)

Infrared radiation has many properties: reflected from objects; bodies that are transparent to visible rays can be opaque to invisible light and vice versa; poorly scattered by the medium, since they have wavelengths longer than that of visible light; are chemically inactive and are used for developing photographic films; have a strong thermal action(slide number 23).

Where are my properties used?

Ilya Muromets:(slides with areas of application appear along with the answer)

Infrared radiation is used in medicine for heating tissues of a living organism; drying of various products; when pasteurizing products; to protect premises from fires; in night vision devices (slide number 24).

OK! Letting go of you!

(visible radiation)

Leading number 2.

And what happened to Alyosha Popovich? What adventures did he get in his way? And the hero came to the kingdom of visible light. A hero walks and sees the light of unearthly beauty (garland).

Alesha Popovich:

Blimey! Red! Orange! Yellow! Green! Blue! Blue! Purple! Oh holy spectrum! Oh magic number seven! (slide number 25) (meets a girl).

Young woman:

Good day to you, hero! Where are you going?

Alesha Popovich:

I came where the road led me. Into the realm of visible light. The path was not close, do not let me die of thirst, give me pure and cool water to drink.

Young woman:

Try the juices produced by our company. Fortified juices are the surest way to health! (7 glasses of water tinted in the colors of the spectrum are taken out *)

* Juices are put in the order of the spectrum.

Alesha Popovich:

Oh, mistress, the juice is delicious! Tell me, mistress, how are things in your kingdom?

Young woman:(along with the answer, slides with the laws of light appear) (slides №26-28). And where does this magical light find application, you know?

Alesha Popovich:

Painting various materials and objects; light music, television; photosynthesis in nature; photograph (slide number 29).

You can carry out a simple and very beautiful experience- experience with tourmaline crystals.

1. 1. Take a rectangular plate of tourmaline and direct a beam of light from an electric lamp to it normally. The rotation of the plate around the beam will not cause any change in the light intensity; the light has only acquired a greenish color. But the light wave acquired new properties.

      These properties are found if a beam of light is forced to pass through a second similar tourmaline crystal, located parallel to the first.

      With identically directed crystal axes, the light beam is further weakened. But if the second crystal is rotated, leaving the first motionless, then the light will be extinguished.

      This can be explained by the fact that light is a transverse wave and the wave beam incident from an ordinary source contains oscillations of all possible directions perpendicular to the direction of wave propagation. Tourmaline crystal has the ability to transmit light waves with vibrations lying in one specific plane. Tourmaline crystal converts natural light into plane-polarized light.

(ultraviolet radiation)

Leading number 2.

Meanwhile, Dobrynya Nikitich ended up in the ultraviolet principality. He walked for a long time, looking for this magical principality in order to ask the great prince, the chief ruler for help in the terrible trouble that happened on his land. So that the ruler of the ultraviolet principality helps him to return the sun to a clear sky, and dry all the fields and meadows on the Russian land, so that the people do not know grief, but live in satiety. And he meets a clear sun on his way (meets the sun).

The sun.

Why did you come to my principality? What trouble has brought you here?

Nikitich.

Trouble happened in my state, terrible torrential rains flooded the entire crop! We are facing an unprecedented famine. Great ruler, help return the clear sun, and dry and warm the Russian land.

The sun.

OK! You just have to tell me what you know about ultraviolet radiation.

Nikitich(slides number 30-36).

The sun.

I'm happy! Return to your homeland and do not be sad! Soon the sun will shine in the sky again!

(x-ray)

Leading number 2.

We are starting the program "News". C vodka incidents. Due to icy conditions, the number of injuries associated with the human bone apparatus has increased. We advise those who find themselves in such a situation to contact our center, where experienced doctors - radiologists are waiting for you. I have some characteristics of the radiation used in the new center (slideshow # 37-42).

(Gamma - radiation)

Leading number 2.

The created center does not in any way affect the overall radiation background in the city, which today is 15 microR / h. Let's turn to our experts for a comment (slide show №43-48).

Teacher.

So our journey on the scale of electromagnetic waves has ended. Hope you enjoyed our little walk. We close the table that you filled out during our trip. Let's check how you understood and memorized the spectra of electromagnetic waves.

Conclusion. Conclusions.

Teacher.

Previously, all information about the Universe was obtained in the visible range using optical telescopes(slide number 49). In the 20th century, it became possible to analyze data coming in the radio range; radio telescopes are used for this. Currently, the study of galaxies and other objects of the Universe is carried out in the infrared, ultraviolet, X-ray ranges using detectors installed on spaceships and satellites.

Spacecraft made it possible to carry out studies of space objects in all ranges of wavelengths of electromagnetic radiation. The slide (slide # 50) is a gamma-ray photograph of the growing moon; x-ray sun; milky way in different ranges.

Conclusions:(slide number 51)

Studies of electromagnetic radiation are of great importance for clarifying our understanding of the structure of matter. Infrared, visible and ultraviolet radiation helped to find out the structure of molecules and outer electron shells of atoms; the study of X-ray radiation made it possible to establish the structure of the inner electron shells of atoms and the structure of crystals, and the radiation of gamma rays gives a lot of valuable information about the structure atomic nuclei.

Analysis of the information obtained in the entire spectrum of electromagnetic waves makes it possible to compile a more complete picture of the structure of objects in the Universe, thereby expanding the boundaries of knowledge of nature.

Test (Slide No. 52) (Appendix No. 2).

Option 1.

1. In what cases does the emission of electromagnetic waves occur?

1. The electron moves uniformly and in a straight line.

2. The electron moves uniformly and rectilinearly.

3. The electron moves uniformly around the circumference.

Answers: A. only 1

B. only 2

B. only 3

G. 1, 2, 3

D. 2 and 3

2. Does electromagnetic radiation occur when electrons are decelerated?

Answers: A. no

B. yes

3. Which of the following radiations are capable of diffraction at the edge of an obstacle?

Answers: A. Radio waves

B. Visible radiation C. X-rays

4. What properties will be detected by electromagnetic waves of the following ranges, falling on the human body? Conduct matching.

1. Radio waves

2. X-ray range

3. Infrared

4.Ultraviolet range.

B. Heat the tissue.

5. What kind of electromagnetic waves has the lowest frequency?

Answers: A. X-ray

B. Ultraviolet

B. Visible light

D. Infrared

E. Radio waves

Option 2.

1. What kind of electromagnetic waves has the longest wavelength?

Answers: A. X-ray

B. Ultraviolet

B. Visible light

D. Infrared

E. Radio waves

2. With what speed does an electromagnetic wave propagate in a vacuum?

Answers: A. 300 km / s

B. 300,000 km / s

V. 30,000 km / s

G. 3000 km / s

3. What properties will be detected by electromagnetic waves of the following ranges, falling on the human body? Conduct matching.

1. X-ray range

2. Radio waves

3. Ultraviolet range

4. Infrared range.

Answers: A. Causes skin redness.

B. Heat the tissue.

B. Almost completely reflected

D. Pass through soft tissue

4. Which of the following emissions are capable of interfering?

Answers: A. Radio waves

B. Visible radiation

V. X-ray

D. Everything except X-rays

E. All of the above emissions

5. Does electromagnetic radiation occur when a charge moves with acceleration?

Answers: A. Yes

B. No

Homework (slide number 53).

§23, Rymkevich –1137.1139.

Repetition of formulas on the topic "Quantum theory" (call the student to the blackboard).

How are the wavelength and frequency of radiation related?

Write down Einstein's equation.

Independent work (according to G. Stepanova's problem book, grade 10-11) (Appendix No. 3).

Option 1.

What is the energy of a photon of red light with a wavelength of 0.72 microns.

Determine the maximum kinetic energy photoelectrons emitted from potassium when it is illuminated by rays with a wavelength of 345 nm. The work function of electrons from potassium is 2.26 eV.

Option 2.

The radiation consists of photons with an energy of 6.4 · 10 -19 J. Determine the frequency and wavelength of this radiation.

The work function of electrons from gold is 4.76 eV. Find the red border of the photo effect for gold.

Summing up (questions for students).

Was the lesson interesting? How?

Have you learned something new?

Would you like to conduct lessons in this manner?