Ultrasonic waves are part of sound waves, is inaudible to the human ear, the frequency is higher than 20KHZ sound waves, it and sound waves have **** the same, that is, they are produced by the vibration of the material and can only be propagated in the medium. Many animals can emit and receive ultrasound, with bats being the most prominent, which can utilize the weak ultrasound echoes to fly in the dark and catch food.
Ultrasonic waves are mechanical oscillations in an elastic medium, which can take two forms: transverse and longitudinal oscillations. Longitudinal oscillation is mainly used in industrial applications. Ultrasonic waves can propagate in gases, liquids and solids at different speeds. In addition, it also has refraction and reflection phenomena, and there is attenuation in the propagation process.
Expanded information:
The propagation of ultrasonic waves in the air, its frequency is low, generally tens of KHZ, while in the solid, liquid, the frequency can be used to higher. In the air attenuation is faster, while in the liquid and solid propagation, attenuation is smaller, spread farther. The use of ultrasound characteristics, can be made into a variety of ultrasonic sensors, with different circuits, made of a variety of ultrasonic measuring instruments and devices, and in communications, medical home appliances and other aspects of a wide range of applications.