Ultrasonic

Ultrasound is a type of sound wave with a frequency higher than 20000 Hz. It has good directionality, strong penetration ability, and is easy to obtain concentrated sound energy. It can propagate over long distances in water and can be used for ranging, velocity measurement, cleaning, welding, gravel, sterilization, and disinfection. There are many applications in medicine, military, industry, and agriculture. Ultrasound is named after its lower frequency limit being greater than the upper limit of human hearing.
Scientists refer to the number of vibrations per second as the frequency of sound, which is measured in hertz (Hz). The frequency of sound waves that can be heard by our human ears is 20Hz-2000Hz. Therefore, we refer to sound waves with frequencies above 20000 Hz as "ultrasound". The frequency commonly used for medical diagnosis is between 1 MHz and 30 MHz.
Theoretical research shows that under the same amplitude conditions, the energy of an object's vibration is directly proportional to the vibration frequency. When propagating in the medium, the frequency of particle vibration in the medium is very high, resulting in a large amount of energy. In the dry winter of northern China, if the water is introduced into a water tank, severe vibration will cause the water in the tank to break into many small droplets. Then, a small fan can be used to blow the droplets into the room, which can increase indoor air humidity, This is the principle of a humidifier. For diseases such as pharyngitis and tracheitis, it is difficult to use blood flow to reach the affected area with medication. Using the principle of a humidifier to atomize the medication and allow the patient to inhale can improve the therapeutic effect. The use of enormous energy can also cause stones in the human body to undergo intense forced vibrations and shatter, thereby alleviating pain and achieving the goal of healing. It is widely used in medicine and can sterilize and disinfect items.