Lesson summary on the topic: “Sound sources. Sound vibrations. Sound waves in physics, grade 9,

Lesson summary on the topic “Sound waves” lesson plan in physics (grade 11) on the topic

GBOU secondary school No. 1112

Podlesnykh Irina Evgenievna

TOPIC: “Sound waves”

Lesson type: lesson on learning new material.

Equipment: tuning fork, glass bell from an air pump, “Hearing Analyzer” table, presentation.

Lesson objectives:

- find out what is the source of sound, determine its characteristics;

— establish a connection between physics, biology and music;

— develop students’ ability to work with text, highlight the main idea;

- develop the interest and cognitive activity of students in the lesson

- cultivate an active attitude towards learning about the world around us.

Lesson plan.

1. Org moment.
2. Updating knowledge.
3. Learning new material. Working with texts.
4. Self-test (test).
5. Lesson summary.
6. Homework.

1. 1) Greeting.

2) Checking students' readiness for work.

3) Organization of attention:

— Guys, look carefully at the tables and diagrams on the board. Think about what we will talk about in class today?

Indeed, the topic of our lesson is “Sound Waves”. We have to find out what is the source of sound, what are its characteristics. Let us recall from the biology course the structure of our ear and try to answer the question of how the ear hears. Let's get acquainted with such interesting phenomena as infrasound and ultrasound. And that's not all. But first, let's remember the basic concepts, the main characteristics of oscillatory and wave motion.

II. Students ask each other questions (oscillatory motion; main characteristics of oscillations: amplitude, period, frequency, phase; wave; longitudinal and transverse waves; wave length, wave speed).

III. 1. From the history of acoustics.

We live in a world of sounds. We are surrounded by the noise of our city, the rustling of leaves, the voices of friends, the sounds of the railway. Some sounds soothe, others lift your spirits, others cause sadness, and others call to action and movement. A person who cannot hear from birth cannot master speech; the world for him is devoid of diversity.

The branch of physics that deals with the study of sound phenomena is called acoustics.

People began to guess about how sounds are born and what they are a very long time ago. We noticed, for example, that sound is created by bodies vibrating in the air. Even the ancient Greek scientist Aristotle, based on observations, correctly explained the nature of sound, believing that a sounding body creates alternating compression and rarefaction of air. Thus, a vibrating string either compresses or discharges the air, thanks to the elasticity of which these alternating effects are transmitted into space from layer to layer, causing elastic sound waves.

Problems of acoustics were of interest to Leonardo da Vinci, G. Galileo, I. Newton, D. Bernoulli, G. Ohm, P. N. Lebedev and other prominent scientists. So much had been done in this area of ​​science that by the end of the 19th century, many scientists considered the further development of acoustic research unpromising. However, within a few decades, this science again occupied the minds of many scientists.

2. Sound sources.

So, the source of sound is always vibrating bodies: strings, a tuning fork, a column of air in wind instruments, etc. And the conductor of sound can be any elastic medium. Our ear perceives vibrations in the form of sound, the frequency of which lies in the range from 20 to 20,000 Hz.

Demonstration. A tuning fork is a curved metal rod on a stem. When struck with a rubber mallet, a tuning fork produces a clear but quiet sound with a frequency of 440 Hz. To improve the sound, a tuning fork is mounted on a resonator box. When a tuning fork sounds, the column of air in the box vibrates. This column vibrates in resonance with the vibrations of the tuning fork, so the tuning fork produces a louder sound. In addition, the sound box is like a horn, directing sound waves in one direction. The glass bell from the air pump also sounds when you hit its edge with a rubber mallet. Due to its large surface, the bell produces a fairly loud sound.

3. How does the ear hear?

Student Report (Appendix)

4. Sound characteristics.

In the auditory sense, sounds vary in pitch, volume and timbre. These physiological characteristics depend on the frequency, amplitude, and shape of the vibrations.

Sound vibrations occurring according to the harmonic law are perceived by humans as a musical sound, or tone.

1. Vibrations of high frequency are perceived as high-pitched sounds. Low frequency sounds are like low pitched sounds.

The pitch of the sound depends on the vibration frequency: the higher the vibration frequency of the sound source, the higher the sound it produces (graph).

The sounds of the male voice are lower than the sounds of the female voice, the sounds of the bass are lower than the sounds of the tenor, and the soprano is higher than the alto.

1. Sound volume: the greater the vibration amplitude, the louder the sound (graph).

With the same amplitudes, we perceive as louder sounds whose frequencies lie in the range from 1000 to 5000 Hz, so a high female voice with a frequency of 1000 Hz will be louder for our ear than a low male voice with a frequency of 200 Hz, even if the amplitude of the vocal cords in both cases is are the same.

1. Timbre.

Everyone knows that sounds of the same pitch, reproduced on different instruments, differ from each other in softness or harshness. The quality of musical sound, its peculiar “coloring” is characterized by timbre. Tuning forks and sound generators create sounds of pure tone (only one frequency), and these are simple, seemingly “fresh” sounds. In a violin or trumpet, vibrations of a more complex shape are generated, which correspond to more complex sounds, beautiful and expressive (graph). Here are some characteristics of timbre: thick, deep, masculine, harsh, velvety, matte, shiny, light, heavy, rich.

“The simple tones that we get from our tuning forks,” Stoletov wrote, “are not used in music, they are as fresh and tasteless as chemically pure water, they are characterless.”

The timbre depends on the material from which the instrument is made and on the shape of the instrument.

- Now let’s work on our own. You are given 5 minutes to read the text, highlight the main idea, and then present it to everyone else.

- Let's listen to how sound travels.

Report No. 1 “Sound Propagation” (appendix).

- Now let's listen to what noise is and how you can deal with it.

Report No. 2 “Noise and the fight against it” (appendix).

Demonstration of different conductivities of substances.

— Our ear perceives vibrations from 20 to 20,000 Hz. Vibrations lying beyond these boundaries are not audible to us, but their nature is identical to sounds, which is why we also call them sounds.

Report No. 3 “Inaudible sounds” (appendix).

— Interest in infrasounds arose after one mysterious incident.

In Marseille (France), a small factory was built next to the scientific center. Soon after its launch, strange phenomena were discovered in one of the scientific laboratories. After staying in her room for a couple of hours, the researcher became absolutely stupid: he had difficulty solving even a simple problem. Such incidents had not been observed before.

And then someone remembered a theatrical miracle that had been sensational in the past. During the course of the play at the Lyric Theater in London, the director needed to create an atmosphere of mystery and horror. All the effects known at that time were tried, but they did not give the required result. By chance, the famous American physicist Robert Wood was present at the rehearsal. He promised to take care of creating the appropriate mood for the actors and spectators, but asked to keep this secret for a while.

The scientist’s authority was so great that his “scenery” was not rehearsed. It was mounted just before the start of the performance. It was just a long, wide pipe made of tin, which was attached to a theater organ. At the right moment, at a sign from the director, the organist began to play. But no one heard the sound. “Complete failure,” the director almost shouted and grabbed his head. Did the scientist make a mistake in his calculations?

But then the crystal pendants on the ancient lamps began to tremble. And everyone present at the performance felt causeless fear. Moreover, for some reason the horses at the entrance became worried, and panic began on the street. The reporter at the time (and newspapers wrote about this) may have exaggerated the story somewhat, but his description is largely plausible.

Did such an organ play near the Marseilles laboratory? This is where the search for the secret of the “enchanted” room began. The reasons turned out to be extremely prosaic. An exhaust pipe was installed in the factory ventilation system, which accidentally turned out to be a source of infrasonic vibrations. And just by chance, the premises in the ill-fated laboratory turned out to be a good resonator of these vibrations. It was not difficult to correct the situation, knowing the true reasons. Scientists and production workers remained good neighbors. (Elshansky I.I. The laws of nature serve people. A book for middle and high school students. M., “Enlightenment”, 1978. P.104-105.)

— Now let’s listen to how ultrasounds help us in our lives.

Report No. 4 “Ultrasound is a human assistant” (appendix)

-What is an echo? How is it formed?

Report No. 5 “Echo” (appendix).

— The name “echo” is associated with the name of the mountain nymph Echo, who, according to ancient Greek mythology, was unrequitedly in love with Narcissus. From longing for her beloved, Echo dried up and became petrified. All that was left of her was a voice capable of repeating the endings of words spoken in her presence.

— Now let’s hear about a very young science – psychoacoustics.

Report No. 6 “Psychoacoustics” (appendix). Brahms' "Lullaby" sounds.

— The achievements of any science can be used both for the benefit and harm of humanity. In our time, science must be moral. Sound can be used to heal, or to zombify, evoking in a person certain emotions that someone needs (the use of acoustic guns in Tbilisi).

IV. Self-test (application).

V. – Guys, I hope that you learned a lot of new things today, and this will encourage you to further independently study sound phenomena.

The lesson is summarized. Lesson grades.

VI. D/z: § 47.

Application

Sound propagation

Wherever we are, no matter what we do, we are accompanied everywhere by various sounds.

A sound wave can travel a wide variety of distances. Gunfire can be heard at 10-15 km, the neighing of horses and barking dogs - at 2-3 km, and whispers - only a few meters. These sounds are transmitted through the air. But not only air can be a conductor of sound.

Put your ear to the rails and you will hear the sound of an approaching train much earlier. This means that metal conducts sound better and faster than air. Good propagation of sound over the ground has long been noticed. Before the Battle of Kulikovo, Prince Dmitry Donskoy himself went out on reconnaissance into the field and, putting his ear to the ground, heard the trampling of horses of the approaching Tatar hordes. Beethoven, deaf, listened to the piano playing, holding one end of his cane to it, the other end of which he held in his teeth. Here the sound conductor was wood.

Water also conducts sound well. Having dived into the water, you can clearly hear the stones knocking against each other, the noise of the pebbles during the surf. Fish hear the footsteps and voices of people on the shore, this is well known to fishermen. The property of water - it conducts sound well - is widely used for reconnaissance at sea during war, as well as for measuring sea depths.

There is only one barrier to sound, and it is easy to detect. If you set an alarm clock and cover it with a cap, the sound will be heard. But if you pump out the air from under the hood, the sound will disappear. Why? Because sound cannot be transmitted through emptiness. There must be an elastic medium. A sound wave is an alternation of condensation and rarefaction. And if there is no medium, then what will condense?

An important event in the development of acoustics was the experimental determination of the speed of sound. In air, the speed of sound was first measured by A. Humboldt in 1822. In water, the speed of sound was determined by Colladon and Sturm in 1827. on Lake Geneva. In 1832, Jean Baptiste Biot measured the speed of sound in a solid body - a cast iron pipe of a Parisian water supply.

According to modern data, the speed of sound in air under normal conditions is 331 m/s.

Noise and dealing with it

According to the effect they have on us, all sounds are divided into musical sounds and noises. How are they different from each other? Pure musical sound always has a certain frequency. Noise is a multitude of very different sounds rushing at the same time.

Noise (especially loud noise) has a harmful effect on people’s health and ability to work. Prolonged exposure to noise causes fatigue. In nature, loud sounds are rare. Sounds and noises of high power affect the hearing aid, nerve centers, and can cause pain and shock. This is how noise pollution works. The quiet rustling of leaves, the murmur of a stream, bird voices, and the sound of the surf are pleasant to man. They calm you down and relieve stress.

Long-term noise adversely affects the hearing organs, reducing sensitivity to sound. It leads to disruption of the heart and liver, and to exhaustion and overstrain of nerve cells.

The noise level is measured in units expressing the degree of sound pressure - decibels. A noise of 130 decibels causes pain in a person’s ear and can even be felt on the skin.

By developing technology, man replaces human labor with the work of machines. And this leads to increased noise. Consequently, new ways to combat it are opening up. Different solids conduct sound in different ways. Elastic bodies are good conductors of sound, soft and porous bodies are poor conductors.

To protect any room from extraneous sounds, the walls, floor and ceiling are covered with layers of materials that do not conduct sound well (felt, carpets, pressed cork, sawdust, porous stones). Motors and machines are covered with shells that absorb sound. Telephone booths are lined with pressed tiles. Sound vibrations, having reached such layers, are damped in them. The energy of vibrational motion in such bodies is converted into internal energy - the bodies heat up.

But it is still very difficult to protect yourself from external noise.

Inaudible sounds

Vibrations with frequencies below 20 Hz are called infrasounds. We can hear infrasounds that lie close to the lower boundary of sound. The fact is that infrasounds, as a rule, are accompanied by audible overtones (overtones). The ear is able to sense the relationship between such infrasounds and sound.

Infrasonic vibrations occur easily in long pipes. For example, a 10-meter organ pipe produces a fundamental tone with a frequency of about 16 Hz. The sound of this trumpet is like thunder. Infrasounds occur in furnace and factory chimneys during combustion.

Phenomena close to infrasound are vibrations that occur during shots and explosions

One of the most interesting types of infrasound is the “voice of the sea”. During a storm at sea, the wind excites vortices that periodically break off on the crests of the waves. The resulting vibrations of the air stream propagate into the distance in the form of infrasound and can be detected at a distance of hundreds of kilometers. Therefore, various marine inhabitants capable of perceiving the “voice of the sea” - jellyfish, crustaceans, sea fleas - feel its approach long before the onset of a storm.

Infrasound waves with a frequency of 6-8 Hz can cause a person’s internal organs to resonate, because the body’s natural frequency is approximately the same. All this can lead to local destruction of internal organs and hemorrhages. In addition, infrasound also affects the human psyche, which leads to inexplicable anxiety and hysteria. Something similar can be observed when the sound of low musical instruments during concerts dramatically changes the mood of listeners.

Ultrasound is a human assistant

Mechanical vibrations occurring with a frequency of more than 20,000 Hz are called ultrasonic. It turned out that they are emitted and perceived by living beings for their “negotiations.” Dogs, for example, perceive ultrasound with a frequency of up to 40 kHz. Trainers use this to give the dog a command that people cannot hear.

Ultrasounds are widely used.

The liquid “boils” when an ultrasonic wave passes through. In this case, water hammer occurs. Ultrasound can be used to mix immiscible liquids. This is how emulsions in oil are prepared.

Under the influence of ultrasound, saponification of fats occurs. Washing devices are designed on this principle.

The biological effects of ultrasound are interesting. Ultrasounds weaken the vital activity of bacteria, reduce the growth of lactic acid and tuberculosis bacteria.

Ultrasound is widely used in hydroacoustics. Ultrasounds of high frequency are absorbed very weakly by water and can spread over tens of kilometers. If they encounter the bottom, iceberg or other solid body in their path, they are reflected and produce an echo of great power. An ultrasonic echo sounder is designed on this principle.

Ultrasound propagates in metal with virtually no absorption. Using the ultrasonic location method, it is possible to detect the smallest defects inside a part of large thickness.

Ultrasound is widely used in medicine to diagnose and treat certain diseases. Diagnostic ultrasound examinations (ultrasound) make it possible to recognize pathological changes in organs and tissues without surgical intervention. Ultrasound therapy is based on the fact that ultrasonic waves of certain frequencies have a mechanical, thermal, physicochemical effect on tissue, as a result of which metabolic processes and immune reactions are activated in the body.

The crushing effect of ultrasound is used to make ultrasonic soldering irons.

Echo

Echoes are sound waves reflected from some obstacle (buildings, hills, forests, etc.) and returned to their source. If sound waves reach us, sequentially reflected from several obstacles and separated by a time interval of 50-60 ms, then a multiple echo occurs. Some of these echoes have become world famous. For example, the rocks spread out in the shape of a circle near Adersbach in the Czech Republic repeat 7 syllables in a certain place, and in Woodstock Castle in England the echo clearly repeats 17 syllables.

The echo phenomenon is used both on ships and submarines. By sending short ultrasound pulses, you can catch their reflections from the bottom or any objects. Based on the delay time of the reflected signal, one can judge the distance to the obstacle.

The creators of radar did not think that many of the technical problems they encountered had been “solved” in nature millions of years ago. It turns out that a radar and a tiny bat have something in common. Night vision in bats is not related to the functioning of the eyes, but to the function of the oral cavity. During flight, the mouse continuously emits ultrasonic pulses from its larynx, directed only in the direction of flight. These waves are well reflected from very small obstacles, which makes it easy to detect prey. At the same time, mice themselves often become the object of hunting, because owls hear ultrasound.

Orientation by reflected sounds was also discovered in cetaceans. Thus, dolphins confidently navigate in muddy water. By sending and receiving ultrasonic pulses that return, they are able to detect even a small pellet carefully lowered into water at a distance of 20-30 m.

Psychoacoustics

Psychoacoustics is a recently emerged branch of the study of human potential, the goal of which is to learn how to change human behavior by studying the influence of sound, speech and music on consciousness.

Music can have a profound effect on brain function. For example, music at a tempo of 60 beats per minute increases the brain's alpha activity (associated with relaxation) by 6%, while beta activity (associated with normal waking consciousness) decreases by 6%. The pulse slows by an average of 4 divisions of mercury, and people report a “state of relaxed consciousness.”

Timbre, the tonality of music, also has a strong influence on brain function.

Dr. Sue Chapman conducted an experiment at New York City Hospital studying the effects of music on babies born prematurely. One group of infants listened to Brahms' Lullaby (variation for string instruments) six times a day, while the other group (the control) did not listen to any music. Newborns who listened to Brahms gained weight faster, suffered fewer complications, and were discharged from the hospital on average a week earlier than those who did not listen to the music.

Psychoacoustics is a young science, and we are only now beginning to understand the precision with which sound forms can influence cellular processes in the brain.

Sound waves. Sound.

1. The condition for excitation of a sound wave is:

1) presence of a source of oscillations;

2) the presence of an elastic medium.

a) only 1

b) only 2

c) 1 and 2.

1. Ultrasonic vibrations are vibrations whose frequency...

a) less than 20 Hz.

b) from 20 to 20000 Hz.

c) exceeds 20,000 Hz.

1. The pitch of the sound depends on...

a) vibration amplitudes.

b) oscillation frequencies.

c) speed of sound.

1. The sound volume depends on...

a) sound frequencies.

b) vibration amplitudes.

c) speed of sound.

1. “Voice of the Sea” - sound vibrations with a frequency...

a) less than 20 Hz.

b) from 20 to 20000 Hz.

c) exceeds 20,000 Hz.

1. Speed ​​of sound in air under normal conditions:

a) 300,000 km/s.

b) 360 m/s.

c) 331 m/s.

1. Which of the following substances conduct sound well?

a) felt.

b) sawdust.

c) metals.

Lesson summary_ Grade 11_ Sound waves and more

Lesson of generalization and in-depth knowledge

“Sound waves and more......”

“Explore everywhere all the time,

What is great and beautiful"

Lesson objectives:

-Generalize and expand knowledge about sound waves, identifying harmful and

useful properties of acoustic waves;

-Expand knowledge about a new type of waves - ultrasonic;

-Show the importance of physical knowledge in human life, maintaining a sustainable interest in the subject;

Tasks:

Educational: - transfer into the system students’ knowledge about sound and types of sound waves;

— introduce new concepts beyond the program level;

- teach how to apply the acquired knowledge in life;

Developmental: - continue the development of speech, thinking, attention;

— show the connection between physics and biology and medicine;

— develop skills in creating multimedia presentations;

Educational: - to arouse interest in the subject through practical significance

the subject being studied;

- give everyone the opportunity to feel their potential

to the student to show the significance of the knowledge gained;

-promote during the lesson the formation of worldviews

concepts;

Lesson type: lesson of generalization and deepening of knowledge

Equipment and aids: vice and ruler, tuning fork, bead on a string, “Ear” poster, multimedia projector, screen, computer, electronic presentations.

During the classes

The first stage is Organizational.

The entire lesson is accompanied by a Presentation.

Slide 1

Teacher: Today we are conducting a lesson on generalizing and deepening knowledge on the topic “Sound waves and more...”

The purpose of this lesson is to summarize the material studied on this topic to expand and deepen knowledge about sound and ultrasonic waves.

Slide 2

If you look closely at the world around you, you will notice that it is all permeated with waves. Waves live everywhere you look. They live their inconspicuous lives and do their work. You should at least take a closer look at yourself: all the veins in you vibrate, the blood moves in waves through the arteries. Electrical impulses travel along the nerves. Impulses (wave packets) go from the eyes to the brain; light waves enter our eyes, and sound waves enter our ears; the larynx produces sounds that are waves. Wave motion is one of the most common types of motion in nature.

One of the important features of waves is that waves transfer energy without transferring matter. Another feature is the ability to transfer information. Today we will be interested in sound waves. Thanks to them we can talk to each other and enjoy music. Man has always lived in a world of sounds (birds singing, the sound of music, the noise of the forest and flowing water); of living beings, only man has used the properties of the environment as a carrier of sound. Man introduced speech and music into the world of sounds and made sound his assistant. What do we know about sound today?

The second stage is updating knowledge

We can check this at this stage of the lesson. Guys, get ready for the homework survey. Each of you worked at home with questions, the answers to which represent the minimum knowledge gained in physics lessons. Let's now try to answer some of them. Attention to the screen.

Slides 3-4

Frontal survey on the material studied:

1. What is sound? (elastic wave, the source of which is an oscillating body).
2. Is any wave sound? (no, only a wave whose particles vibrate at a certain frequency).
3. Is it possible to somehow confirm this statement experimentally? (yes, you can use a ruler clamped in a vice. By deflecting the end of the ruler from the equilibrium position, we will excite its vibrations. The vibrations will be perceived by our ear only when the protruding end of the ruler is so short that its vibrations will occur at the sound frequency).
4. What must be the frequency range of a vibrating body for a person to hear sound? (frequency should be in the range from 17 to 20000 Hertz).
5. What characteristics of elastic waves, including sound waves, do you know? (wavelength, period, frequency, wave speed).
6. What are the objective physical characteristics of sound waves? (sound pressure, sound intensity, sound spectrum).
7. What characteristics of sound would you classify as subjective characteristics? (volume, pitch, timbre).
8. How do you explain the volume of the sound? (amplitude of vibrations of the sound source).
9. Is it possible to verify this statement experimentally? (yes, for this you will need a tuning fork and a bead suspended on a thread. By placing a bead next to the tuning fork and striking the tuning fork with different forces, you will notice that the bead will vibrate with different amplitudes. The sound of the tuning fork will be louder then. When the amplitude of vibrations is greater its branches).
10. What does the pitch of sound depend on? (the height depends on the vibration frequency of the source; the more frequencies, the higher the sound).
11. How can sounds of the same frequency and volume differ from each other? (sounds differ in timbre).
12. In what media does sound travel? (sound travels in all media, with the exception of vacuum).
13. It is known that elastic waves can be longitudinal and transverse. What are sound waves? (sound waves are longitudinal, but transverse sound waves can also propagate in solids; their speed will be lower).

Teacher: you did a good job with this part of your homework. I will look at the notebooks with problem solving after the lesson. Today I will collect the workbooks from the students sitting in the front row. And we continue.

Slide 5

Third stage - Expansion of knowledge

Teacher: Some of you, in the process of studying the topic, received advanced tasks related to searching for information from a wide range of sources. You can see some of them in printed form in front of you. And some of you, having received such a task, prepared multimedia presentations for it. Now you have to become active listeners and evaluate the results of their work. Everyone has “Score Cards” on their desks. Listening carefully to the speaker's message, try to evaluate: the technical execution of the presentation, its content and the speech culture of the author. For each, give a final score and remember that your feedback will determine the speaker’s score.

People began to guess a long time ago how sounds are born and what they are. The ancient Greek philosopher Aristotle, based on observations, correctly explained the nature of sound. He believed that a sounding body creates alternating compression and rarefaction of air. Thanks to the elastic properties of air, this process spreads in space, from layer to layer, creating a sound wave. When it reaches our ear, it impacts the eardrums and causes the sensation of sound. What's next? The first speaker will tell us about this.

Slides 6-15

Student 1 makes a report on the topic “The ear is a natural receiver of sound waves.”

Teacher: Now try to guess the children's riddle.

Slide 16

Every call is answered.

But there is neither soul nor body. (Echo)

Teacher: Due to the finite speed of sound, an echo appears. You know that an echo is a sound wave reflected by some obstacle and returned to the place from where it began to propagate. Obstacles can be mountains or the edge of a forest. High wall. We hear an echo after a period of time during which the sound wave travels to the obstacle and back, i.e. travels twice the distance between the sound source and the obstacle. By emitting short pulses of waves and catching their echo, they measure the time it takes the wave to travel to the obstacle and back, and then determine the distance to it. This is the essence of echolocation. But sound waves cannot travel strictly in one direction due to their long wavelength. Therefore, ultrasonic waves are used for echolocation. But they are strongly absorbed in the air and weakly in water, so echolocation is mainly used in water - sonar. Let's find out more about this.

Slides 17-26

Student 2 Makes a report on the topic “About underwater acoustics and hydroacoustics”

Slide 27

Teacher: When the Allied forces entered Germany at the end of the Second World War, technical experts began an intensive search for works and patents related to ultrasound. The fact is that in Germany in the 30s of the 20th century, a lot of fundamental research was carried out on the practical application of sound waves, the frequencies of which lie above the upper limit of the frequencies perceived by the human ear. A thousand words are not enough to describe all the applications of ultrasound. Let's limit ourselves to just a few of them.

Slides 28-39

Student 3 Makes a report on the topic “Ultrasonic flaw detection”

Slides 40-46

Student 4 Makes a report on the topic “Ultrasonic locator guide for the blind”

Slides 47-64

Student 5 Gives a report on the topic “Ultrasound in medicine”

Slide 65

Teacher: Ever since the technological revolution gave man new sources of energy of unprecedented power, people began to somehow not treat their planet properly. The “costs” of technological progress can be seen at every step. Pits and ditches filled with garbage; junkyards for rusting cars; rivers and lakes dying from industrial waste; The air we breathe is polluted by the smoke and exhaust fumes of millions of cars. However, there is an even more sinister companion to the development of the industry, which is more dangerous for people than polluting waste - noise. Noise pollution in the atmosphere is constantly increasing. Noise has a harmful effect on human health. Of course, in our lesson we cannot ignore this very important issue for us. Let's hear another message about noise, its impact on people's mental health and noise control.

Slides 66-72

Student 6 Makes a report on the topic “Noise”

Slide 73

Stage four - Lesson summary

Teacher: To summarize, I would like to say a few words about the fact that many outstanding people, such as the composer Beethoven, the scientist Tsiolkovsky, had difficulty perceiving sounds - they were simply deaf. But, nevertheless, they continued to create, creating works of genius. It turns out that in some forms of deafness, when the auditory nerve is not damaged, sound passes through the bones. Sometimes deaf people can dance, perceiving the rhythm of the music due to the vibrations of the floor. It is known that the great composer Beethoven, being deaf, listened to music with the help of a cane, one end of which he leaned on the piano, holding the other in his teeth. Human capabilities are limitless, even a serious illness is not a hindrance. A person must constantly, day after day, strive for the heights of mastery, for the search for something new, for perfection.

Slide 74

Well, our lesson is coming to an end. And I would like to end it with the words of the brilliant scientist Albert Einstein:

“A day in which you learn nothing is a wasted day. We have so much to learn, we don’t have much time for it.”

Don't waste your time, try to learn more about the world in which we live. After all, the desire to learn and expand your knowledge about what you already know is a natural need of any sane person.

I hope the Scorecards summed it up for you. I will study them carefully and, taking into account your opinion, I will give each a final grade.

Stage five - homework

As you already understand, today we talked to you about the practical application of ultrasonic waves. But you know about the existence of waves with a frequency lower than the threshold of human audibility - infrasound.

Homework: Using the Internet, collect and present information about infrasound.

Summary of an integrated lesson in physics on the topic “Sound waves” (grade 11)

Physics 11th grade

Lesson topic: Sound waves

Lesson type: combined lesson

Type of lesson: integrated lesson (physics, biology, music)

Lesson Objectives

Educational:

1. introduce the concept of “sound wave”,
2. find out what is the source of the sound,
3. introduce students to the characteristics of sound, teach them to distinguish sounds by volume, tone, timbre; show how these characteristics are related to the frequency and amplitude of vibrations;
4. show the connection between physics, biology and music.

Educational:

1. activate the cognitive process,
2. development of logical and abstract thinking.

Educational:

1. to help introduce students to the world of beauty,
2. broadening one's horizons,
3. development of cognitive interest in physics, biology, music;
4. promotion of healthy lifestyles.

Equipment: multimedia complex, flute, rattle, tuning fork with hammer, metal ruler, vice.

Lesson plan:

1. Organizing time.
2. Information input from the teacher on the topic of the lesson.
3. Learning new material.
4. Consolidation of the studied material. Solving quality problems.
5. Summing up the lesson.
6. Homework.

During the classes.

1. Organizing time.
2. Information input from the teacher on the topic of the lesson.

The student plays a melody from the movie “Titanic” on the flute.

Music teacher. What piece of music and what movie did you just hear from? What instrument was played for you now?

Historical reference. The flute is one of the oldest musical instruments; official sources date its appearance to 35 - 40 thousand years BC. But perhaps this amazing musical instrument is much earlier.

The prototype of a flute is an ordinary whistle, the sound of which appears when a stream of air oscillates, which is cut by the sharp edge of a tree or other material.

There were different types of whistles; they were made of clay, stone, and wood. They existed among most peoples as various signaling devices, children's toys and as musical instruments.

Later, holes were cut in the whistle tube, by clamping which it was possible to adjust the pitch of the sound. Chromatic frets were formed using finger combinations and closing the holes halfway or one-quarterway. An increase in sound by an octave occurred by increasing the strength or direction of breathing. Gradually, the whistle tube became longer, and there were more holes. The sound range expanded, the melodies and playing techniques became more complex.

Modern flutes are divided into several main types. This is a longitudinal recorder; transverse flute, which has many varieties; Pan flute is a multi-barrel flute.

The transverse flute is now the most common musical instrument of the flute family. It was known in Egypt more than five thousand years ago and still remains the main wind instrument throughout the Middle East. In Rus', a type of longitudinal flute was the pipe; it is not possible to date its appearance.

In China, the transverse flute has been known for more than three thousand years, in India and Japan for more than two thousand years.

The transverse flute entered Central Europe from the East through the Balkans, where it still remains the most widespread folk instrument. The transverse flute was repeatedly improved by European masters until it acquired the modern form we know.

Physics teacher.

The world of sounds is so diverse, Rich, beautiful, varied, But we are all tormented by the question: Where do the sounds come from, That delight our ears everywhere? It's time to think seriously.

Why does sound occur? How are the sounds different? What is sound? How is it transmitted and received? Today we will try to answer all these questions.

1. Learning new material.

Physics teacher. Let's find out what is the source of the sound.

The teacher demonstrates an experiment with a tuning fork, shows a rattle and makes sounds with it.

What and who else can make sounds?

Student answers: musical instruments, people, animals, birds, sea.

What is the source of any sounds?

Student answer: hesitation.

Indeed, the source of sound is a vibrating body.

Does every oscillating body make a sound? Give examples when bodies vibrate but do not sound.

Students give examples.

An experiment is demonstrated with a metal ruler clamped in a vice.

Why are sounds heard in some cases and not in others?

It turns out that a person perceives sounds with a frequency from 16 to 20,000 Hz. Such vibrations are called acoustic. Elastic waves that are perceived by human hearing are called sound waves. The branch of mechanics that studies sound waves is called acoustics.

Biology teacher. Among animals, birds and fish, there are species that perceive and produce sounds that humans cannot hear.

In many caves bats live in huge colonies. They are in caves only during the day, but at night they fly out and hunt for insects. How do these animals fly in complete darkness, without bumping into walls or limestone formations? It turned out that bats are capable of emitting and perceiving ultrasonic vibrations. The frequency of these emitted vibrations is about 50 thousand per second.

Most bats have large ears, with an open edge at the bottom; in front of the ear canal there is a leathery protrusion - the tragus. Vision is poorly developed, so all bats determine the position of surrounding objects (including food items) by catching echoes of ultrasonic signals with their hearing aids (short ultrasonic pulses with a frequency of 20-120 kHz and a duration of 0.2 to 100 ms). Location signals are created by the larynx and emitted through the nose or mouth.

The first part of the pulses falls on the wall and is reflected at an angle equal to the angle of incidence. In addition, a side wave arises, which falls on the wall, runs along its entire surface, intersects with the first wave and turns back to the place from which it originated. This means that thanks to ultrasound and a side wave capable of turning back, bats can not only fly inside and outside the cave, perfectly oriented in pitch darkness, but also catch small insects in flight.

One species of marine mammal that uses ultrasound is dolphins. The volumes of those parts of the brain that manage auditory functions are tens (!) times greater than in humans (despite the fact that the total volume of the brain is approximately the same). The dolphin is capable of perceiving frequencies of sound vibrations 10 times higher (up to 150 kHz) than humans (up to 15-18 kHz), and hears sounds whose power is 10-30 times lower than that of sounds accessible to human hearing, such as No matter how good a dolphin’s vision is, its capabilities are limited due to the low transparency of the water. Most dolphins have a dorsal fin and a snout that extends into a “beak.” Of the cetacean family, dolphins have the best developed echolocation and the most sensitive hearing.

Ultrasound arises in the larynx, passes into the air sacs of the head, which are an ultrasound amplifier, and these rays, passing through the fat lens, are collected at one point near the fish. These rays can travel a distance of up to 15-20m.

And American scientists have discovered that tigers and elephants use not only growls, purrs or roars and trumpet calls to communicate with each other, but also infrasound, that is, very low frequency sound signals that are inaudible to the human ear. Ed Walsh and his colleagues at Boys Town National Research Hospital in Omaha, Nebraska, analyzed the frequency spectra of the growls of representatives of three subspecies of tigers - Ussuri, Bengal and Sumatran - and found in each of which a powerful low-frequency component. According to scientists, infrasound allows animals to maintain communication at a distance of up to 8 kilometers, since the propagation of infrasound signals is almost insensitive to interference caused by terrain, and depends little on weather and climatic factors such as air humidity.

Dogs perceive ultrasound with frequencies up to 40 kHz. Trainers use this to give the dog a command that people cannot hear.

Physics teacher. Ultrasound and infrasounds have found wide application in our lives. Let's hear a message about where ultra and infrasounds have been used.

Student message. Today, ultrasound is used in a huge number of industries. Among them: medicine, geology, steel industry, military industry, etc. Ultrasound is used extremely intensively in geology; there is a special science - geophysics.

Using ultrasound, geophysicists find deposits of valuable minerals and determine the depth of their location.

In the metal foundry industry, ultrasound is used to diagnose the state of the metal crystal lattice. When “listening” to pipes and beams of high-quality products, a certain signal is obtained, but if the product has something different from the norm (density, design defect), the signal will be different, which will indicate to the engineer that it is defective.

Modern medicine also uses ultrasound. For example, one of the most common procedures using it is ultrasound, where ultrasound is used to diagnose the condition of internal organs. Ultrasound physiotherapy is also used to accelerate the regeneration of scars, tissues, and bone fusion; ultrasound cardiogram, ultrasound osteosynthesis. Ultrasonic teeth cleaning is the safest and most effective way to clean the surface of teeth. Ultrasound is used to destroy microorganisms and sterilize medical instruments. Vascular ultrasound is the main method for diagnosing varicose veins.

Surrounded by enemy ships, the submarine has only one safe

The way to contact the base is to transmit a signal in the aquatic environment. For this, a special conditioned ultrasonic signal of a certain frequency is used - it is almost impossible to intercept such a message, because To do this, you need to know its frequency, exact transmission time and “route”. However, sending a signal from a boat is also a complex procedure - it is necessary to take into account all the depths, water temperature, etc. The base, receiving the signal and knowing its travel time, can calculate the distance to the boat and, as a result, its location.

Today, all kinds of devices using ultrasonic pulses have become widespread. And it spreads not only in industry, but also in the economy of modern Russians. One of the most famous devices is an ultrasonic washing machine: a small “tablet” that connects to the network and washes without detergents. This device receives the most positive reviews: washing is silent and economical - the device requires very little auxiliary detergents and consumes less energy than a 50-watt light bulb, the laundry is not only cleaned, but also disinfected.

Piezoceramic emitters excite ultrasonic vibrations, which form a huge number of microscopic bubbles in the solution with high pressure inside, which, when exploding, disrupt the adhesion of contaminated microparticles to the fibers of products and facilitate their removal by surfactants of the washing solution, washing powder or soap. Thus, the cleaning of fabric fibers occurs from the inside...