<<–2/”>a >a href=”https://exam.pscnotes.com/sound/”>Sound is a longitudinal wave, in which the particles oscillate to and fro in the same direction of wave propagation. Sound waves cannot be transmitted through vacuum. The transmission of sound requires at least a medium, which can be solid, liquid, or gas.
Newton to derive a relation for the velocity of sound in a gaseous medium, assumed that compression and rarefaction caused by the sound waves during their passage through the gas take place under isothermal condition. This means that the changes in volume and pressure take place at constant temperature. Under such conditions, Newton agreed that the velocity of sound wave in a gas is given by v = ?(P/ ?)
Frequency is the number of oscillations completed by an oscillator in one second. It is denoted by v. The SI unit of frequency is hertz (symbol Hz). Since v is the number of oscillations per second, the time taken to complete one oscillation is 1/v. Hence T =1/v or v = (1/T) s–1.
Sound waves are divided into three categories that cover different frequency ranges.
(1) Audible waves lie within the range of sensitivity of the human ear. They can be generated in a variety of ways, such as by Musical instruments, human voices, or loudspeakers.
(2) Infrasonic waves have frequencies below the audible range. Elephants can use infrasonic waves to communicate with each other, even when separated by many kilometers. Various animals like Elephants, Whale and Rhino produces Infrasonic waves. Sources of infrasound in nature include Volcanoes-2/”>Volcanoes, avalanches, Earthquakes and meteorites.
(3) Ultrasonic waves have frequencies above the audible range. You may have used a “silent” whistle to retrieve your dog. The ultrasonic sound it emits is easily heard by dogs, although humans cannot detect it at all. Ultrasonic waves are also used in medical imaging
Ultrasonic sound characteristics
- They have a high energy content.
- Just like ordinary sound waves, ultrasonic waves get reflected, refracted and absorbed.
- They can be transmitted over large distanceswith no appreciable loss of energy.
- If an arrangement is made to form stationary waves of ultrasonics in a liquid, it serves as a diffraction grating. It is called an acoustic grating.
- They produce intense heating effect when passed through a substance.
Ultrasonic waves are used for the following purposes.
1. Ultrasonic flaw detection.
2. Cutting and matching of hard materials.
3. Ultrasonic soldering and welding.
4. Measurement of flow devices.
5. Applications in medicine.
6. Thermal effect.
7. Ultrasonic as means of Communication.,
Mechanical waves are waves that are created by the movement of matter. They can travel through solids, liquids, and gases. Some examples of mechanical waves include sound waves, water waves, and seismic waves.
Audible waves are mechanical waves that can be heard by humans. They have frequencies between 20 and 20,000 hertz. Sound waves are produced when an object vibrates. The vibration causes the air Molecules around the object to vibrate as well. These vibrations travel through the air in the form of waves. When the waves reach our ears, they cause our eardrums to vibrate. Our brains interpret these vibrations as sound.
Infrasonic waves are mechanical waves that have frequencies below 20 hertz. Humans cannot hear infrasonic waves, but some animals, such as elephants, can. Infrasonic waves can travel long distances through the air and through solid objects. They are often used in communication and in the detection of earthquakes.
Ultrasonic waves are mechanical waves that have frequencies above 20,000 hertz. Humans cannot hear ultrasonic waves, but they are used in a variety of applications, such as medical imaging, non-destructive testing, and pest control. Ultrasonic waves are produced by electronic devices called ultrasonic transducers. These transducers convert electrical energy into ultrasonic waves.
The main characteristics of mechanical waves are amplitude, frequency, wavelength, speed, direction of propagation, medium, reflection, refraction, diffraction, interference, and standing waves.
Amplitude is the maximum displacement of the particles of the medium from their equilibrium position. Frequency is the number of waves that pass a given point in a given amount of time. Wavelength is the distance between two consecutive crests or troughs of a wave. Speed is the distance traveled by a wave in a given amount of time. Direction of propagation is the direction in which a wave travels. Medium is the material through which a wave travels. Reflection is the bouncing back of a wave when it hits a surface. Refraction is the bending of a wave when it passes from one medium to another. Diffraction is the spreading of a wave as it passes through an opening or around an obstacle. Interference is the interaction of two or more waves that results in a new wave pattern. Standing waves are waves that form when two waves of the same frequency and amplitude travel in opposite directions.
Mechanical waves can be classified into two types: transverse waves and longitudinal waves. Transverse waves are waves in which the particles of the medium move perpendicular to the direction of the wave. Longitudinal waves are waves in which the particles of the medium move parallel to the direction of the wave.
Mechanical waves can also be classified by their speed. The speed of a wave depends on the properties of the medium through which it is traveling. The speed of a wave is also affected by the frequency of the wave.
Mechanical waves are important in many aspects of our lives. They are used in communication, in transportation, and in many other applications.
Mechanical waves
Mechanical waves are waves that propagate through a material medium (solid, liquid, or gas) due to the oscillation of matter in the medium. The medium itself does not move, but the energy associated with the wave travels through the medium.
Mechanical waves can be classified into two types: longitudinal waves and transverse waves. Longitudinal waves are waves in which the particles of the medium move parallel to the direction of the wave. Transverse waves are waves in which the particles of the medium move perpendicular to the direction of the wave.
The speed of a mechanical wave depends on the properties of the medium through which it is traveling. The speed of a wave is equal to the square root of the product of the elastic modulus of the medium and the density of the medium.
The frequency of a mechanical wave is the number of waves that pass a given point in a given amount of time. The wavelength of a mechanical wave is the distance between two consecutive crests or troughs of the wave.
The amplitude of a mechanical wave is the maximum displacement of the particles of the medium from their equilibrium position.
Audible waves
Audible waves are mechanical waves that can be heard by humans. The frequency of audible waves ranges from 20 Hz to 20,000 Hz.
Audible waves are produced by vibrating objects. The vibration of an object causes the air molecules around the object to vibrate. These vibrating air molecules then collide with other air molecules, causing them to vibrate as well. This process continues, with the sound waves traveling through the air until they reach our ears.
Our ears are able to detect sound waves because they have tiny hairs inside them that vibrate when sound waves hit them. These vibrations are converted into electrical signals that are sent to our brain, which interprets them as sound.
Infrasonic waves
Infrasonic waves are mechanical waves with frequencies below the range of human hearing. The frequency of infrasonic waves ranges from 0 Hz to 20 Hz.
Infrasonic waves are produced by a variety of sources, including earthquakes, volcanoes, and thunder. They can also be produced by human activities, such as traffic and industrial machinery.
Infrasonic waves can travel long distances and can penetrate through solid objects. This makes them useful for a variety of applications, such as communication, surveillance, and geophysical exploration.
Ultrasonic waves
Ultrasonic waves are mechanical waves with frequencies above the range of human hearing. The frequency of ultrasonic waves ranges from 20,000 Hz to 100,000,000 Hz.
Ultrasonic waves are produced by a variety of sources, including piezoelectric crystals, magnetostrictive materials, and spark-gap generators. They can also be produced by human activities, such as ultrasonic cleaning and ultrasonic welding.
Ultrasonic waves have a number of properties that make them useful for a variety of applications, such as non-destructive testing, medical imaging, and cleaning.
Main characteristics of mechanical waves
The main characteristics of mechanical waves are:
- Amplitude: The maximum displacement of the particles of the medium from their equilibrium position.
- Frequency: The number of waves that pass a given point in a given amount of time.
- Wavelength: The distance between two consecutive crests or troughs of the wave.
- Speed: The distance traveled by a wave in a given amount of time.
- Direction of propagation: The direction in which the wave travels.
- Medium: The material through which the wave travels.
- Source: The object that produces the wave.
- Observer: The person or object that detects the wave.
Which of the following is not a type of mechanical wave?
(A) Audible wave
(B) Infrasonic wave
(C) Ultrasonic wave
(D) Electromagnetic WaveAudible waves are waves that can be heard by humans. The frequency of audible waves is between 20 Hz and 20 kHz. Which of the following is not an example of an audible wave?
(A) Sound of a dog barking
(B) Sound of a bird chirping
(C) Sound of a car honking
(D) Sound of a microwave ovenInfrasonic waves are waves with frequencies below 20 Hz. Which of the following is not an example of an infrasonic wave?
(A) Sound of a volcano erupting
(B) Sound of a jet engine taking off
(C) Sound of a heartbeat
(D) Sound of a cricket chirpingUltrasonic waves are waves with frequencies above 20 kHz. Which of the following is not an example of an ultrasonic wave?
(A) Sound of a bat using echolocation
(B) Sound of a dog whistle
(C) Sound of a dentist’s drill
(D) Sound of a baby cryingWhich of the following is not a characteristic of mechanical waves?
(A) They can travel through matter.
(B) They can be transverse or longitudinal.
(C) They can be polarized.
(D) They can be amplified.Which of the following is not a characteristic of audible waves?
(A) They can be heard by humans.
(B) They have frequencies between 20 Hz and 20 kHz.
(C) They can be used to create music.
(D) They can be used to communicate.Which of the following is not a characteristic of infrasonic waves?
(A) They have frequencies below 20 Hz.
(B) They can be used to detect earthquakes.
(C) They can be used to create music.
(D) They can be used to communicate.Which of the following is not a characteristic of ultrasonic waves?
(A) They have frequencies above 20 kHz.
(B) They can be used to detect flaws in materials.
(C) They can be used to create music.
(D) They can be used to communicate.