Chapter-12 Sound

Explanation:

When a vibrating object produces sound, it creates a series of compressions and rarefactions in the surrounding medium (such as air, water, or a solid material). These compressions and rarefactions form a sound wave that propagates outward from the source in all directions.

When the sound wave reaches your ear, it first encounters the outer ear, which consists of the pinna (the visible part of the ear) and the ear canal. The pinna helps to collect and direct sound waves into the ear canal, which is a narrow, tube-like structure that leads to the eardrum.

As the sound wave enters the ear canal, it causes the eardrum to vibrate. The eardrum is a thin, flexible membrane that separates the outer ear from the middle ear. When the eardrum vibrates, it sets the three tiny bones in the middle ear (the malleus, incus, and stapes) into motion.

The motion of these bones amplifies the sound wave and transmits it to the inner ear, which is filled with fluid. As the sound wave enters the fluid-filled inner ear, it causes tiny hair cells in the cochlea (a spiral-shaped organ in the inner ear) to vibrate. These hair cells convert the mechanical vibrations of the sound wave into electrical signals, which are transmitted to the brain via the auditory nerve.

Finally, the brain processes these electrical signals and interprets them as sound, allowing you to hear the sound produced by the vibrating object.

Explanation:

The school bell typically consists of a metal bell-shaped object and an electromechanical device called a striker, which hits the bell to produce sound.

When the school bell is activated, an electrical current flows through a wire in the electromechanical device, creating an electromagnetic field. This electromagnetic field pulls a small metal piece (the armature) toward the electromagnet, causing the striker attached to the armature to move toward the bell.

As the striker strikes the bell, it causes the bell to vibrate. These vibrations travel through the air as sound waves and are perceived by the ear as sound.

The pitch and volume of the sound produced by the school bell depend on the size, shape, and material of the bell, as well as the force and speed of the striker's impact. The duration of the sound is controlled by a timer or switch, which opens or closes the circuit and stops the flow of electricity to the electromechanical device, causing the striker to stop hitting the bell.

Overall, the process of sound production in a school bell involves the conversion of electrical energy into mechanical energy, which then produces sound waves that travel through the air and are perceived by the ear.

Explanation:

Sound waves are called mechanical waves because they require a medium, such as air, water, or a solid material, to propagate. In other words, sound waves cannot travel through a vacuum, such as outer space, where there is no medium to carry the wave.

Mechanical waves are waves that require a medium to travel, and they propagate by causing particles in the medium to vibrate back and forth in the direction of the wave's motion. In the case of sound waves, the vibrating particles are the molecules of the medium (such as air molecules), which compress and rarefact (move apart) as the sound wave propagates through them.

Explanation:

No, you will not be able to hear any sound produced by your friend on the moon, as there is no atmosphere to transmit sound waves.

Sound waves require a medium, such as air, to propagate. On the moon, however, there is no atmosphere, and thus no air or other medium to transmit sound waves. As a result, any sound produced on the moon would have no way to travel through the vacuum of space and reach your ears.

Explanation:

The two wave properties that determine loudness and pitch are amplitude and frequency, respectively.

(a) Loudness is determined by the amplitude of a sound wave. The amplitude of a sound wave is the maximum displacement of the particles of the medium (such as air molecules) from their rest position as the wave passes through the medium. The greater the amplitude of the sound wave, the more energy it carries and the louder it sounds. For example, a sound wave with a larger amplitude will cause greater vibrations in the eardrum and thus be perceived as louder.

(b) Pitch is determined by the frequency of a sound wave. The frequency of a sound wave is the number of cycles of vibration per second, measured in Hertz (Hz). The higher the frequency of the sound wave, the higher the pitch of the sound. For example, a sound wave with a higher frequency will cause more frequent vibrations in the eardrum and thus be perceived as a higher-pitched sound.

Explanation:

Based on typical pitch ranges for musical instruments and common environmental sounds, it is likely that the guitar has a higher pitch than a car horn.

A guitar typically produces sounds within a range of frequencies that can vary depending on the specific note being played, but generally falls within the range of 82 Hz to 1,396 Hz for the six strings of a standard guitar.

In contrast, a car horn typically produces a single tone with a frequency of around 400 Hz to 500 Hz, which is relatively lower in pitch compared to the range of the guitar.

Therefore, it is likely that the guitar has a higher pitch than a car horn.

Explanation:

A sound wave can be described by several key properties, including its wavelength, frequency, time period, and amplitude.

1.Wavelength: The wavelength of a sound wave is the distance between two consecutive points in the wave that are in phase, such as two consecutive peaks or two consecutive troughs. It is denoted by the symbol λ (lambda) and is measured in meters (m). The wavelength of a sound wave is related to its frequency by the formula λ = v/f, where v is the velocity of the wave in the medium and f is its frequency.

2.Frequency: The frequency of a sound wave is the number of cycles per second, measured in Hertz (Hz). It is denoted by the symbol f and is related to the pitch of the sound. Higher frequencies correspond to higher-pitched sounds, while lower frequencies correspond to lower-pitched sounds.

3.Time period: The time period of a sound wave is the time it takes for one complete cycle of vibration to occur, measured in seconds (s). It is denoted by the symbol T and is related to the frequency of the wave by the formula T = 1/f.

4,Amplitude: The amplitude of a sound wave is the maximum displacement of the particles of the medium (such as air molecules) from their rest position as the wave passes through the medium. It is denoted by the symbol A and is related to the loudness of the sound. Larger amplitudes correspond to louder sounds.

Explanation:

The wavelength and frequency of a sound wave are inversely proportional to each other and are both related to the speed of the wave.

The speed of sound in a medium, such as air, is determined by the properties of the medium, such as its temperature, density, and elasticity. It is denoted by the symbol v and is typically measured in meters per second (m/s).

The wavelength of a sound wave, denoted by the symbol λ, is the distance between two consecutive points in the wave that are in phase. The frequency of a sound wave, denoted by the symbol f, is the number of cycles per second.

The relationship between wavelength, frequency, and speed of a sound wave can be described by the formula:

v = λ × f

This formula states that the speed of sound in a medium is equal to the product of the wavelength and frequency of the sound wave.

Since wavelength and frequency are inversely proportional to each other, if the frequency of a sound wave increases, its wavelength decreases, and vice versa, while the speed remains constant.

Therefore, the wavelength and frequency of a sound wave are related to its speed through this formula, which indicates that they are inversely proportional to each other, while the speed remains constant

Explanation:

The wavelength of a sound wave can be calculated using the formula:

λ = v / f

where λ is the wavelength, v is the speed of sound, and f is the frequency of the sound wave.

In this case, the frequency is given as 220 Hz and the speed of sound is given as 440 m/s. Substituting these values into the formula, we get:

λ = 440 m/s / 220 Hz

Simplifying, we get:

λ = 2 m

Therefore, the wavelength of the sound wave is 2 meters in the given medium

Explanation:

The time interval between successive compressions from the source of a sound wave is also known as the time period of the wave. It can be calculated using the formula:

T = 1 / f

where T is the time period and f is the frequency of the sound wave.

In this case, the frequency is given as 500 Hz. We can use the speed of sound in air to calculate the wavelength of the sound wave, and then use the formula for wave speed to find the time period.

The speed of sound in air at room temperature is approximately 343 meters per second. The wavelength of the sound wave can be calculated using the formula:

λ = v / f

where λ is the wavelength and v is the speed of sound. Substituting the values, we get:

λ = 343 m/s / 500 Hz

λ = 0.686 meters

Now, we can use the formula for wave speed to find the time period of the wave:

v = λ / T

Solving for T, we get:

T = λ / v

Substituting the values, we get:

T = 0.686 meters / 343 m/s

T = 0.002 seconds

Therefore, the time interval between successive compressions from the source of the sound is 0.002 seconds.

Explanation:

Loudness and intensity are two different characteristics of sound that are often confused with each other. While both are related to the perceived loudness of a sound, they are measured and defined in different ways.

Loudness is a subjective perception of how loud or soft a sound appears to the human ear. It depends on the intensity of the sound wave as well as the sensitivity of the human ear to different frequencies of sound. Loudness is measured in decibels (dB) on a logarithmic scale, with 0 dB representing the threshold of hearing and 120 dB representing the threshold of pain.

Intensity, on the other hand, is a physical measure of the amount of energy that a sound wave carries per unit area per unit time. It is typically measured in watts per square meter (W/m²). The intensity of a sound wave depends on the amplitude (or height) of the wave, which determines how much energy is being carried by the wave.

Explanation:

Sound travels fastest in solids, such as iron, because the particles in solids are closer together and can transmit vibrations more quickly than in liquids or gases.

In general, the speed of sound in air is approximately 343 meters per second at room temperature and standard atmospheric pressure. The speed of sound in water is approximately 1482 meters per second, which is about four times faster than in air. The speed of sound in iron is even faster, typically around 5000 meters per second.

Therefore, sound travels the fastest in iron, followed by water, and then air.

Explanation:

The time taken for a sound wave to travel from a source to a reflecting surface and back to the source is twice the time taken for the sound to travel from the source to the reflecting surface. This is because the sound wave has to travel twice the distance in order to complete a round trip.

In this case, the time taken for the sound wave to travel from the source to the reflecting surface and back is 3 seconds. Therefore, the time taken for the sound wave to travel from the source to the reflecting surface is half of this, or 1.5 seconds.

We can use the formula for wave speed to calculate the distance between the source and the reflecting surface:

v = d / t

where v is the speed of sound, d is the distance between the source and the reflecting surface, and t is the time taken for the sound wave to travel this distance.

Substituting the values given, we get:

342 m/s = d / 1.5 s

Solving for d, we get:

d = 342 m/s x 1.5 s

d = 513 meters

Therefore, the distance between the source and the reflecting surface is 513 meters.

Explanation:

The ceilings of concert halls are curved for a number of reasons, all of which are related to the acoustics of the space. The main reasons are:

1.Improved sound distribution: A curved ceiling helps to distribute sound evenly throughout the concert hall. The curved shape allows sound waves to reflect off the ceiling and disperse in multiple directions, rather than bouncing off in a single direction as they would with a flat ceiling. This creates a more immersive and natural sound experience for the audience.

2.Reduced echo: A curved ceiling helps to reduce the amount of echo and reverberation in a concert hall. Echoes occur when sound waves bounce off surfaces and return to the listener with a delay. A curved ceiling helps to break up these echoes and prevent them from interfering with the original sound. This improves the clarity of the sound and makes it easier for the audience to hear individual instruments and voices.

3.Better acoustics for different types of music: Different types of music require different acoustics in a concert hall. For example, classical music typically requires a longer reverberation time than rock music. By curving the ceiling, concert hall designers can create a space with more variable acoustics that can be adjusted to suit different types of music.

Explanation:

The audible range of the average human ear is typically considered to be between 20 Hz and 20,000 Hz (or 20 kHz). This range can vary slightly depending on factors such as age, gender, and exposure to loud noises over time.

Explanation:

(a) Infrasound is typically defined as sound with frequencies below the lower limit of the audible range for humans, which is usually considered to be around 20 Hz. Infrasound frequencies can range from 0.1 Hz to 20 Hz.

(b) Ultrasound is typically defined as sound with frequencies above the upper limit of the audible range for humans, which is usually considered to be around 20,000 Hz or 20 kHz. Ultrasound frequencies can range from 20 kHz up to several gigahertz (GHz), although the upper limit of ultrasound is not well-defined and can vary depending on the source.

Explanation:

We can use the formula:

distance = speed x time

where the speed is the speed of sound in salt water and the time is the time it takes for the sonar pulse to travel to the cliff and back.

The time taken for the sonar pulse to travel to the cliff and back is 1.02 s, so the total distance traveled by the sonar pulse is:

distance = speed x time

distance = 1531 m/s x 1.02 s

distance = 1561.62 m

However, this distance is the total distance traveled by the sonar pulse, so we need to divide it by two to get the distance from the submarine to the cliff:

distance from submarine to cliff = 1561.62 m / 2

distance from submarine to cliff = 780.81 m

Therefore, the cliff is 780.81 meters away from the submarine.

Explanation:

Sound is a type of energy that travels through a medium, such as air, water, or solids, in the form of waves. These waves are created by the vibration of an object, which causes the surrounding medium to vibrate as well. This vibration creates a disturbance in the medium, which propagates as a sound wave and can be detected by our ears.

Sound can be produced by any object that is capable of vibrating. When an object vibrates, it creates a disturbance in the surrounding medium, which causes the particles in the medium to vibrate as well. These vibrations cause the pressure of the medium to fluctuate, creating compressions and rarefactions in the medium. The compressions are areas where the particles are closer together, while the rarefactions are areas where the particles are further apart.

As the sound wave travels through the medium, it causes these compressions and rarefactions to propagate through the medium. When the wave reaches our ears, it causes our eardrums to vibrate, which in turn sends signals to our brain, allowing us to perceive the sound.

Explanation:

When the school bell is hit with a hammer, it moves forward and backwards, producing compression and rarefaction due to vibrations. When it moves forward, it creates high pressure in its surrounding area. This high-pressure region is known as compression. When it moves backwards, it creates a low-pressure region in its surrounding. This region is called rarefaction.

Explanation:

One classic experiment that demonstrates that sound requires a medium for its propagation is the Kundt's Tube experiment. Kundt's Tube was invented by German physicist August Kundt in 1866 to measure the speed of sound in different gases and solids.

The experiment involves a long, hollow tube filled with a fine powder, such as lycopodium or cork dust. A source of sound, such as a tuning fork, is placed at one end of the tube, and a piston at the other end is used to vary the length of the tube. When the tuning fork is struck, it produces sound waves that travel down the tube. As the sound waves encounter the powder, they cause it to vibrate and form distinct patterns, known as Kundt's Figures.

The key observation in this experiment is that Kundt's Figures are only produced when the tube is filled with a material medium, such as air or other gases. If the tube is evacuated, i.e., emptied of all gases, the powder remains undisturbed, and no Kundt's Figures are formed. This observation indicates that a material medium is required for sound waves to propagate and produce Kundt's Figures.

In conclusion, the Kundt's Tube experiment is a classic demonstration that sound requires a material medium for its propagation, and it provides a clear visual representation of the interaction between sound waves and a medium.

Explanation:

A sound wave is called a longitudinal wave because the vibrations that produce it are parallel to the direction of the wave's propagation.

In a longitudinal wave, the particles of the medium through which the wave travels oscillate back and forth in the direction of the wave's propagation. The oscillations cause regions of compression and rarefaction to form in the medium, which correspond to the high and low-pressure regions of the sound wave, respectively.

Explanation:

There are several characteristics of sound that can help you identify your friend's voice while sitting with others in a dark room. These characteristics include:

1.Pitch: The pitch of a sound refers to how high or low it is. Each person's voice has a unique pitch, which can help you identify them. For example, if your friend has a high-pitched voice, you may be able to identify them even if you can't see them in the dark room.

2.Timbre: The timbre of a sound refers to its unique quality or tone. Each person's voice has a distinct timbre, which can help you differentiate between them. For example, your friend's voice may have a husky or nasal quality that is different from the voices of others in the room.

3.Intensity: The intensity of a sound refers to its volume or loudness. If your friend speaks in a loud or soft voice, this can help you identify them even in the absence of visual cues.

Explanation:

The reason why thunder is heard a few seconds after the flash is seen is because light travels faster than sound. When lightning strikes, it produces a sudden and intense release of energy in the form of light, which travels at a speed of approximately 299,792,458 meters per second (in a vacuum). In comparison, sound waves produced by the thunder travel at a much slower speed of approximately 343 meters per second (in air at sea level).

As a result, the light from the lightning reaches our eyes almost instantaneously, while the sound of the thunder takes some time to reach our ears. The time delay between the flash and the sound depends on the distance between the observer and the lightning strike, and it can be estimated by counting the number of seconds between seeing the flash and hearing the thunder, and then multiplying that number by the speed of sound.

For example, if you see a lightning strike and hear the thunder 5 seconds later, it means that the lightning strike was approximately 1,715 meters (5 seconds multiplied by 343 meters per second) away from you.

Explanation:

The wavelength of a sound wave can be calculated using the formula:

wavelength = speed of sound / frequency

Where the speed of sound in air is 344 m/s at room temperature and atmospheric pressure.

For a frequency of 20 Hz, the wavelength of the sound wave can be calculated as:

wavelength = 344 m/s / 20 Hz

wavelength = 17.2 meters

Therefore, the typical wavelength of a 20 Hz sound wave in air is approximately 17.2 meters.

For a frequency of 20 kHz, the wavelength of the sound wave can be calculated as:

wavelength = 344 m/s / 20,000 Hz

wavelength = 0.0172 meters

Therefore, the typical wavelength of a 20 kHz sound wave in air is approximately 0.0172 meters, or 17.2 millimeters.

In summary, the typical wavelengths of sound waves in air corresponding to a person's hearing range of 20 Hz to 20 kHz are approximately 17.2 meters and 17.2 millimeters, respectively.

Explanation:

The speed of sound waves in a material depends on the elasticity and density of the material. In general, sound travels faster in solids than in air.

The speed of sound in air at room temperature is approximately 344 m/s, while the speed of sound in aluminum is approximately 5000 m/s.

Let's assume that the aluminum rod is long enough such that the time taken by sound to travel through the air from one end to the other can be neglected compared to the time taken by sound to travel through the aluminum.

The time taken by the sound wave to travel through the aluminum rod can be calculated using the formula:

time = distance / speed

Let the length of the aluminum rod be L. The time taken by the sound wave to travel from one end of the rod to the other end is:

time_aluminum = L / speed_aluminum

Similarly, the time taken by the sound wave to travel through the air can be calculated using the formula:

time = distance / speed

Let the distance between the two children be D. The time taken by the sound wave to travel through the air is:

time_air = D / speed_air

Therefore, the ratio of times taken by the sound wave in the air and in aluminum to reach the second child is:

time_air / time_aluminum = (D / speed_air) / (L / speed_aluminum)

= (D / L) * (speed_aluminum / speed_air)

= (D / L) * (5000 m/s / 344 m/s)

= 14.53 * (D / L)

Therefore, the ratio of times taken by the sound wave in the air and in aluminum to reach the second child is 14.53 times the ratio of the distance between the two children to the length of the aluminum rod.

Explanation:

The frequency of a sound wave is the number of complete vibrations or cycles that the source of sound makes in one second.

If the frequency of the source of sound is 100 Hz, it means that the source vibrates 100 times per second. To find out how many times it vibrates in a minute, we need to multiply the frequency by the number of seconds in a minute:

Vibrations per minute = Frequency x 60 seconds

Vibrations per minute = 100 Hz x 60 seconds

Vibrations per minute = 6000 vibrations

Therefore, a source of sound with a frequency of 100 Hz vibrates 6000 times in one minute.

Explanation:

Yes, sound follows the same laws of reflection as light does. The laws of reflection state that when a wave is reflected from a surface, the angle of incidence (the angle between the incident wave and the normal to the surface) is equal to the angle of reflection (the angle between the reflected wave and the normal to the surface).

For example, if a sound wave hits a flat surface at a certain angle, the wave will be reflected back at an equal angle on the other side of the normal. This is the same as what happens with light waves when they hit a flat mirror.

Similarly, the laws of reflection also apply when a sound wave hits a curved surface. In this case, the angle of incidence is measured relative to the tangent to the surface at the point of incidence, and the angle of reflection is measured relative to the same tangent line. This is the same as what happens with light waves when they are reflected from a curved surface like a lens.

Explanation:

Yes, the speed of sound changes with temperature, and this affects the production of an echo. On a hotter day, the speed of sound is faster than on a cooler day, which means that the time it takes for sound waves to travel a certain distance is shorter.

If a sound wave is reflected from a distant object and travels back to the listener, the listener hears an echo. The time it takes for the sound wave to travel from the source to the reflecting object and back to the listener determines the delay between the original sound and the echo.

On a hotter day, the speed of sound is faster, so the distance the sound wave travels is covered in a shorter time. This means that the delay between the original sound and the echo is shorter than it would be on a cooler day. As a result, the echo is heard sooner and may be perceived as being closer to the original sound.

Explanation:

The reflection of sound waves has several practical applications, including:

1.Sonar: Sonar (sound navigation and ranging) is a technique that uses sound waves to locate and detect objects underwater. A device called a sonar transducer emits a sound wave, which travels through the water and bounces off objects like submarines, rocks, and fish. The reflected sound waves are detected by the sonar receiver, which calculates the time delay and intensity of the reflected waves to determine the location and size of the objects. This technology is used in marine exploration, navigation, and defense.

2.Acoustic design: The reflection of sound waves can be used in architectural and acoustic design to control the sound quality of a room. For example, sound-absorbing materials can be placed on walls and ceilings to reduce sound reflections, resulting in a quieter room with less reverberation. On the other hand, sound-reflecting surfaces can be strategically placed to enhance the acoustics of a concert hall or auditorium, making the music sound clearer and more vibrant. This technology is used in various settings, including concert halls, recording studios, theaters, and classrooms.

Explanation:

We can use the formula:

time taken = time for stone to fall + time for sound to travel

Let's first find the time it takes for the stone to fall from the top of the tower to the pond using the formula:

distance = 0.5 * g * t^2

where g is the acceleration due to gravity and t is the time taken.

500 = 0.5 * 10 * t^2

Simplifying this equation, we get:

t^2 = 100

t = 10 seconds

So, the time taken for the stone to fall is 10 seconds.

Now, let's find the time taken for the sound to travel from the splash to the top of the tower. We can use the formula:

distance = speed * time

where distance is the distance travelled by sound, speed is the speed of sound, and time is the

time taken.

The distance travelled by sound is the same as the height of the tower, which is 500 meters.

So, the time taken for the sound to travel is:

time = distance / speed = 500 / 340 = 1.47 seconds (approx)

Therefore, the total time taken for the splash to be heard at the top is:

time taken = time for stone to fall + time for sound to travel

= 10 + 1.47

= 11.47 seconds (approx)

So, the splash will be heard at the top of the tower after approximately 11.47 seconds.

Explanation:

The formula relating the speed of sound, its frequency and wavelength is given by:

v = fλ

where v is the speed of sound, f is the frequency, and λ is the wavelength.

We are given the speed of sound v = 339 m/s and the wavelength λ = 1.5 cm = 0.015 m.

Substituting these values into the equation, we get:

339 m/s = f × 0.015 m

Solving for f, we get:

f = 339 m/s ÷ 0.015 m

f = 22,600 Hz

Therefore, the frequency of the sound wave is 22,600 Hz.

Whether the sound wave is audible or not depends on the human ear's sensitivity to different frequencies. The human ear can typically detect frequencies between 20 Hz and 20,000 Hz, so a sound wave with a frequency of 22,600 Hz would not be audible to most people. However, some individuals, especially young children and individuals with sensitive hearing, may be able to hear higher frequencies

Explanation:

Reverberation is the persistence of sound in a space after the original sound source has stopped. It is caused by sound waves reflecting off surfaces such as walls, floors, and ceilings, and then interacting with one another in a complex way.

Reducing reverberation in a room can improve the clarity and intelligibility of speech and music, and create a more pleasant listening or recording environment. Here are a few ways to reduce reverberation:

Absorbent materials: Install acoustic panels or sound-absorbing materials on the walls, floors, and ceilings to absorb sound waves and reduce their reflections. This could include materials such as acoustic foam, fiberglass, or even heavy curtains or carpets.

Diffusers: Install sound diffusers on the walls to scatter sound waves and prevent them from reflecting directly back to the listener. Diffusers are typically made of materials such as wood or plastic and can be designed in a variety of shapes and sizes.

Room layout: The layout of the room can also affect reverberation. Avoid placing hard, reflective surfaces opposite each other, and try to place absorptive materials near the sound source.

Furniture: Adding soft furniture such as couches, chairs, and drapes can also help to absorb sound waves and reduce reverberation.

Explanation:

The loudness of sound is a subjective perception of the intensity or amplitude of sound waves. It is often measured in decibels (dB) and corresponds to the physical energy of sound waves that reaches our ears.

The loudness of sound depends on several factors, including:

1.Amplitude: The amplitude of sound waves determines the physical energy of the sound and can influence the perceived loudness.

2.Frequency: The frequency of sound waves refers to the number of cycles per second and can also affect the perceived loudness. In general, sounds with lower frequencies are perceived as louder than sounds with higher frequencies at the same amplitude.

3.Distance: The distance between the listener and the sound source can also affect the perceived loudness. As the distance increases, the sound waves spread out and the intensity decreases.

4.Environment: The environment in which the sound is heard can also affect the perceived loudness. For example, a sound may seem louder in a quiet room compared to a noisy environment.

Explanation:

Bats have the ability to produce high-pitched ultrasonic squeaks. These squeaks get reflected by objects, like prey, and return to their ears. This helps a bat to know how far its prey is.

Explanation:

Ultrasound can be used for cleaning through a process called ultrasonic cleaning. This process involves immersing an object in a liquid and using ultrasound waves to create high-frequency pressure waves that cause microscopic bubbles to form and collapse rapidly. This process is known as cavitation and generates high-energy shock waves that can remove dirt, dust, and other contaminants from the surface of the object.

The process of ultrasonic cleaning typically involves the following steps:

1.Cleaning solution preparation: A cleaning solution is prepared by adding a suitable detergent or solvent to water.

2.Immersion: The object to be cleaned is placed in a tank filled with the cleaning solution.

3.Ultrasonic cleaning: Ultrasound waves are generated by a transducer and directed into the cleaning solution. The waves create cavitation bubbles that implode on the surface of the object, removing dirt and contaminants.

4.Rinsing: The object is rinsed thoroughly with water to remove any remaining cleaning solution.

5.Drying: The object is dried using a suitable method, such as air drying or wiping with a cloth.

Explanation:

Sonar, which stands for Sound Navigation And Ranging, is a technology that uses sound waves to detect and locate objects underwater. It is based on the principle of echolocation, which is the ability of some animals such as dolphins and bats to use sound waves to locate objects in their environment.

The working of a sonar can be explained in the following steps:

Generation of sound waves: A sonar system generates a sound wave, typically at a frequency between 20 kHz and several hundred kHz, and sends it into the water. This sound wave is known as a ping.

1.Reflection of sound waves: When the sound wave encounters an object in the water, it is reflected back towards the sonar system.

2.Reception of reflected sound waves: The sonar system receives the reflected sound wave and measures the time it took for the wave to travel from the sonar to the object and back. This time delay is known as the echo time.

3.Calculation of distance and location: Based on the echo time and the speed of sound in water, the sonar system can calculate the distance to the object and its location.

Sonar technology has many applications in various fields, including:

1.Navigation: Sonar is used to determine the depth of water and to create underwater maps.

2.Marine biology: Sonar is used to study marine life and to locate schools of fish.

3.Military: Sonar is used by navies for submarine detection and by underwater minesweepers.

4.Fishing: Sonar is used by fishermen to locate fish and to identify the composition of the ocean floor.

Explanation:

The speed of sound in water can be calculated using the formula:

speed = distance / time

where distance is the distance traveled by the sound wave and time is the time it takes for the wave to travel that distance.

In this case, we know that the distance of the object from the submarine is 3625 m and the time it takes for the echo to return is 5 s. Therefore, we can calculate the speed of sound in water as follows:

speed = distance / time

speed = 3625 m / 5 s

speed = 725 m/s

Therefore, the speed of sound in water is 725 m/s.

Explanation:

Ultrasound can be used to detect defects in a metal block by generating and analyzing ultrasonic waves that pass through the metal. This process is known as ultrasonic testing or ultrasonic inspection.

The basic principle of ultrasonic testing is that sound waves travel through materials at different speeds depending on the density and elastic properties of the material. When a sound wave encounters a defect or a change in the material's properties, such as a crack or a void, part of the wave is reflected back to the surface. This reflected wave is detected by a receiver and analyzed to identify the location and size of the defect.

The process of ultrasonic testing typically involves the following steps:

1.Preparation: The surface of the metal block is cleaned and a coupling agent, such as oil or water, is applied to improve the transmission of ultrasound waves.

2.Generation of ultrasonic waves: An ultrasonic transducer is placed on the surface of the metal block and emits high-frequency sound waves.

3.Detection of reflected waves: The transducer also serves as a receiver and detects the reflected waves that bounce back from the internal structure of the metal block.

4.Analysis: The reflected waves are analyzed to determine the presence, location, and size of any defects.

Explanation:

The human ear is a complex organ that is responsible for detecting and processing sound waves. The ear can be divided into three main parts: the outer ear, the middle ear, and the inner ear.

1.Outer ear: The outer ear is the part of the ear that is visible on the outside of the head. It consists of the pinna (the visible part of the ear) and the ear canal. The pinna helps to collect sound waves and direct them into the ear canal.

2.Middle ear: The middle ear is located behind the eardrum and contains three tiny bones called the ossicles (malleus, incus, and stapes). When sound waves reach the eardrum, they cause it to vibrate, which in turn causes the ossicles to vibrate.

3.Inner ear: The inner ear is located within the temporal bone of the skull and consists of the cochlea, the vestibule, and the semicircular canals. The cochlea is responsible for detecting sound waves and converting them into electrical signals that can be interpreted by the brain.

The process of hearing can be explained in the following steps:

1.Sound waves enter the outer ear and are collected by the pinna.

2.The sound waves travel down the ear canal and reach the eardrum, causing it to vibrate.

3.The vibrations of the eardrum cause the ossicles to vibrate, amplifying the sound waves.

4.The vibrations of the ossicles are transmitted to the oval window, a membrane that separates the middle ear from the inner ear.

5.The vibrations of the oval window cause fluid in the cochlea to move, which stimulates tiny hair cells in the cochlea to bend.

6.The bending of the hair cells triggers the release of chemicals that create electrical signals, which are sent to the auditory nerve.

7.The auditory nerve carries the electrical signals to the brain, where they are interpreted as sound.

Overall, the human ear is a remarkable organ that enables us to hear and interpret a wide range of sounds in our environment.