<<–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.,
Sound is a form of energy that travels in waves. It is produced by vibrating objects, and it can travel through air, water, and other materials. When sound waves reach our ears, they cause our eardrums to vibrate. These vibrations are then converted into electrical signals that are sent to our brains, where they are interpreted as sound.
The speed of sound depends on the medium through which it is traveling. In air, sound travels at about 343 meters per second. In water, it travels at about 1,500 meters per second. In steel, it travels at about 5,000 meters per second.
The frequency of sound is the number of waves that pass a given point in a given amount of time. It is measured in Hertz (Hz). One Hertz is equal to one wave per second. The human ear can hear sounds with frequencies between about 20 Hz and 20,000 Hz.
Sounds with frequencies below 20 Hz are called infrasonic sounds. Infrasonic sounds are too low for humans to hear, but they can be felt. Some animals, such as elephants, can hear infrasonic sounds.
Sounds with frequencies above 20,000 Hz are called ultrasonic sounds. Ultrasonic sounds are too high for humans to hear, but they can be used for a variety of purposes, such as medical imaging and pest control.
Sources of Infrasonic sound In nature
Infrasonic sounds can be produced by a variety of natural sources, such as earthquakes, volcanoes, and meteor impacts. They can also be produced by animals, such as elephants, whales, and bats.
Elephants use infrasonic sounds to communicate with each other over long distances. Whales use infrasonic sounds to navigate and to find food. Bats use ultrasonic sounds to navigate and to hunt insects.
Ultrasonic sound characteristics and some applications
Ultrasonic sounds have a number of characteristics that make them useful for a variety of applications. They are very high-pitched, so they can travel through materials that would block or absorb lower-frequency sounds. They are also very directional, so they can be used to create images or to detect objects.
Ultrasonic sounds are used in a variety of applications, including medical imaging, pest control, and industrial inspection.
Medical imaging: Ultrasonic waves can be used to create images of the inside of the body. This is done using a device called an ultrasound scanner. The scanner emits ultrasonic waves, which bounce off of the Tissues and organs inside the body. The waves are then reflected back to the scanner, which creates an image of the inside of the body.
Pest control: Ultrasonic waves can be used to repel pests, such as rodents and insects. The waves are at a frequency that is too high for humans to hear, but they can be heard by pests. The waves cause the pests to become uncomfortable and to leave the area.
Industrial inspection: Ultrasonic waves can be used to inspect materials for defects. The waves are passed through the material, and any defects will cause the waves to reflect back in a different way. This can be used to detect cracks, voids, and other defects in materials.
Concept and nature of sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.
Wave length and frequency
The wavelength of a sound wave is the distance between two consecutive compressions or rarefactions in the wave. The frequency of a sound wave is the number of waves that pass a given point in a given amount of time.
Infrasonic and Ultrasonic sounds
Infrasound is sound with frequencies below the range of human hearing, generally below 20 Hz. Ultrasound is sound with frequencies above the range of human hearing, generally above 20 kHz.
Sources of Infrasonic sound In nature
Some sources of infrasound in nature include:
- Earthquakes
- Volcanic eruptions
- Thunderstorms
- Wind
- Ocean waves
- Animals, such as elephants, whales, and hippopotamuses
Ultrasonic sound characteristics and some applications
Ultrasound is characterized by its high frequency and short wavelength. This makes it ideal for a variety of applications, including:
- Medical imaging, such as ultrasound scans
- Non-destructive testing
- Cleaning
- Welding
- Pest control
- Sonar
- Communication
- Sound is a form of energy that travels in waves. The distance between two consecutive peaks or troughs of a wave is called the wavelength. The number of waves that pass a given point in a given amount of time is called the frequency.
- Infrasonic sounds are sounds with frequencies below 20 Hz. Ultrasonic sounds are sounds with frequencies above 20 kHz.
- Some sources of infrasonic sound in nature include earthquakes, volcanoes, and thunder. Some sources of ultrasonic sound in nature include bats, dolphins, and insects.
- Ultrasonic sound has a number of applications, including medical imaging, non-destructive testing, and pest control.
Here are some MCQs on the topic of sound:
Which of the following is not a characteristic of sound?
(A) Wavelength
(B) Frequency
(C) Amplitude
(D) TemperatureThe human ear can hear sounds with frequencies between 20 Hz and 20 kHz. Which of the following sounds is outside of this range?
(A) A whisper
(B) A dog whistle
(C) A clap of thunder
(D) A jet engineInfrasonic sounds are used by some animals to communicate. Which of the following animals uses infrasonic sounds to communicate?
(A) Bats
(B) Dolphins
(C) Elephants
(D) All of the aboveUltrasonic sounds are used in some medical imaging techniques. Which of the following medical imaging techniques uses ultrasonic sounds?
(A) X-rays
(B) CT scans
(C) MRI scans
(D) UltrasoundUltrasonic sounds are used in some non-destructive testing techniques. Which of the following non-destructive testing techniques uses ultrasonic sounds?
(A) Ultrasonic testing
(B) Magnetic particle inspection
(C) Liquid penetrant inspection
(D) Radiographic testingUltrasonic sounds are used in some pest control techniques. Which of the following pest control techniques uses ultrasonic sounds?
(A) Rodenticides
(B) Insecticides
(C) Ultrasonic pest control devices
(D) All of the above