The term ultrasonics is said to be the vibrations of frequencies which is greater than the upper limit of the audible range for humans that is greater than about 20 kilohertz. The term sonic is said to be applied to waves that are ultrasound of very high amplitudes. The hypersound which is sometimes known as praeter sound or the microsound is the waves of sound of frequencies that is greater than 1013 hertz.
At such a high level of frequencies, i.e a frequency of about 1.25 × 1013 hertz, it is very difficult for a wave of sound to propagate efficiently. It is impossible for the longitudinal waves to propagate at all even in a liquid or a solid. That is because the molecules of the material in which the waves are traveling that cannot pass the vibration along rapidly enough.
Ultrasonic Machine
Ultrasound is the wave of sound with frequencies that is higher than the upper audible limit of human hearing. The ultrasound is not different from “normal” that is the audible sound in its physical properties. Except that humans cannot hear it. This limit is said to vary from person to person and is approximately 20 kilohertz that is written as 20,000 hertz in healthy young adults. The devices that are the ultrasound devices operate with frequencies from 20 kHz up to several gigahertz.
Ones is used in many different fields. The term that is ultrasonic devices that are used to detect objects and measure distances. By imagining the ultrasound or sonography is often used in medicine. In the nondestructive testing which is of structures and products. The ultrasound is said to be used in detecting invisible flaws.
Industrially the term that is ultrasound is used for cleaning, and mixing, and accelerating processes that are chemical. Animals such as bats generally use ultrasound voice for locating prey and obstacles as well.
The term that is acoustics which is the science of sound starts as far back as Pythagoras in the 6th century BC who wrote on the properties which are the mathematical properties of stringed instruments. In 1794 echolocation which are in bats was discovered by Lazzaro Spallanzani when he demonstrated that bats hunted and navigated by inaudible sound. In 1893 Francis Galton invented the Galton whistle that is an adjustable whistle that produced ultrasound which he used to measure the hearing range of humans and other animals as well. This was demonstrating that many animals could hear sounds above the hearing range of humans. In 1917 the first application of the technology of ultrasound was an attempt to detect submarines by Paul Langevin. The effect, which is known as piezoelectric, was generally discovered by Jacques and Pierre Curie in 1880 which was useful in transducers to generate and detect ultrasonic waves in air and water.
Ultrasonic Frequency
The term that is sounds with a frequency of 20 kHz and higher are said to be referred to as ultrasound or we can say ultrasonic sound. We can say that the high frequency sound is sound of which the frequency lies between 8 and 20 kHz. The sound which is the high frequency sound with a frequency over 16 kHz can hardly be heard but it is not completely inaudible. The sound which is the high frequency sound and even ultrasound in the lower frequency zone that is up to 24 kHz can be audible if the sound level is high enough. The sound that threshold is the level of the sound where sound can be perceived that usually rises sharply once the frequency and therefore the tone) becomes higher. A person who is younger hears high frequency sound better and their hearing range is greater toward the high frequencies.
The term that is ultrasound and sound of the frequencies that are of high range are widely applied in the industry and health care and also in movement detectors, the range finders and remote controls as well. We can notice that typical for these applications is that their sound levels are low and that the sound frequency usually lies below 100 kHz. The applications that are the medical and industrial generally make use of a wider range of ultrasound frequencies which is up to MHz and usually use much higher sound levels.
Ultrasonic Vibration
The wavelength or the vibrations that are beyond the audible limit of the ear of the humans are called ultrasonic or supersonic vibrations.
These vibrations have very possibilities that are interesting in the field of investigative dermatology. The purpose that is of my brief preliminary report is to call this subject to the attention of dermatologists which is as there are few reports that are on it in our literature.
The frequencies which are most commonly used in various biological, and medical, and commercial, and military applications have ranged from 100 to 1500 kilocycles.
The waves that are the ultrasonic waves generally differ from electromagnetic ones in that they do not traverse a vacuum.
The term Ultrasonics is a name which is given to various specific topics in which the properties of ultrasound are exploited. The ultrasound is simply sound whose frequency is too high to be heard by the ear of human beings, that is to say the frequency is above c 20 kHz.
HOW IT WORKS
In the realm of physics, ultrasonics falls under the category of studies in sound. Sound itself fits within the larger heading of wave motion, which is in turn closely related to vibration, or harmonic (back-and-forth) motion. Both wave motion and vibration involve the regular repetition of a certain form of movement; and in both, potential energy (think of the energy in a sled at the top of a hill) is continually converted to kinetic energy (like the energy of a sled as it is sliding down the hill) and back again.
10 Important Properties of Ultrasonic Waves
Property 1: Ultrasonic waves vibrate at a frequency greater than the audible range for humans (20 kilohertz).
Property 2: They have smaller wavelengths. As a result, their penetrating power is high.
Property 3: They cannot travel through vacuum.
Property 4: Ultrasonic waves travel at the speed of sound in the medium. They have maximum velocity in a denser medium.
Property 5: In a homogeneous medium, they travel at a constant velocity.
Property 6: In low viscosity liquids, ultrasonic waves produce vibrations.
Property 7: They undergo reflection, refraction and absorption.
Property 8: They have high energy content. They can be transmitted over a large distance without much loss of energy.
Property 9: They produce intense heat when they are passed through objects.
Property 10:Like sound waves, ultrasonic waves are longitudinal waves that produce alternate compressions and rarefactions.
Transducers
An ultrasonic transducer is a device used to convert some other type of energy into an ultrasonic vibration. There are several basic types, classified by the energy source and by the medium into which the waves are being generated. Mechanical devices include gas-driven, or pneumatic, transducers such as whistles as well as liquid-driven transducers such as hydrodynamic oscillators and vibrating blades. These devices, limited to low ultrasonic frequencies, have a number of industrial applications, including drying, ultrasonic cleaning, and injection of fuel oil into burners. Electromechanical transducers are far more versatile and include piezoelectric and magneto strictive devices. A magneto strictive transducer makes use of a type of magnetic material in which an applied oscillating magnetic field squeezes the atoms of the material together, creating a periodic change in the length of the material and thus producing a high-frequency mechanical vibration. Magneto strictive transducers are used primarily in the lower frequency ranges and are common in ultrasonic cleaners and ultrasonic machining applications.
Applications in research
One of the important areas of scientific study in which ultrasonics has had an enormous impact is cavitation. When water is boiled, bubbles form at the bottom of the container, rise in the water, and then collapse, leading to the sound of the boiling water. The boiling process and the resulting sounds have intrigued people since they were first observed, and they were the object of considerable research and calculation by the British physicists Osborne Reynolds and Lord Rayleigh, who applied the term cavitation to the process of formation of bubbles. Because an ultrasonic wave can be used carefully to control cavitation, ultrasound has been a useful tool in the investigation of the process. The study of cavitation has also provided important information on intermolecular forces.
Research is being carried out on aspects of the cavitation process and its applications. A contemporary subject of research involves emission of light as the cavity produced by a high-intensity ultrasonic wave collapses. This effect, called sonoluminescence, can create instantaneous temperatures hotter than the surface of the Sun.
The speed of propagation of an ultrasonic wave is strongly dependent on the viscosity of the medium. This property can be a useful tool in investigating the viscosity of materials. Because the various parts of a living cell are distinguished by differing viscosities, acoustical microscopy can make use of this property of cells to “see” into living cells, as will be discussed below in Medical applications.
