Uses of ultrasound in life?

Ultrasonic waves are a type of sound wave, which is a mechanical wave, i.e., a longitudinal wave produced by the vibration of an object, and the number of vibrations per second is called the frequency of the sound wave (in hertz: Hz).

The sound waves produced by the tuning fork above caused the water to vibrate

Similar to the human eye, which can only see certain wavelengths (roughly 300 nanometers to 700 nanometers), the human ear can only hear sound waves at frequencies of roughly 20 hertz to 20,000 hertz. The human ear can only hear sound waves with frequencies ranging from roughly 20 hertz to 20,000 hertz, with frequencies above 20,000 hertz being called ultrasound.

How are ultrasound waves discovered?

The human ear cannot hear ultrasound, but some animals can. In 1794, Spallanzani discovered that bats navigate by an inaudible sound.

In 1876 Galton invented the dog whistle, a special whistle that emits sound waves with a frequency of 20,000 hertz to 50,000 hertz, which is beyond the limits of human hearing, but which can be heard by cats and dogs, since the upper limit of a dog's hearing range is about 40,000 hertz, and the upper limit of a cat's hearing is roughly 60,000 hertz.

So ultrasonic waves were discovered roughly 200 years ago, and the real application of ultrasonic waves can be applied, is after the discovery of the piezoelectric effect by Pierre Curie, the husband of Madame Curie, and his brother in 1880, which can be based on the piezoelectric effect to emit and detect ultrasonic waves, thus opening the door to the application of ultrasonic waves.

Characteristics of ultrasound

Because wavelength and frequency are inversely proportional to each other, and ultrasound frequency is relatively high, so the wavelength is short, which means that ultrasound has a good directionality, and because of the short wavelength, the frequency is high, and the vibration is strong, so it has a high energy.

Ultrasonic waves also have good penetration, so they can spread a longer path within the material. Based on these characteristics, the application of ultrasound is also divided into two main areas.

Ultrasonic applications

Because of the good directionality and strong penetration, there are two main areas of application, the first is the detection and probing, such as ultrasound commonly used in medicine, according to the body's reflection pattern of ultrasound to probe the internal structure of the human body, and the human body is little damage to the human body, it is indispensable to the clinical medicine of a diagnostic method.

There are also sonar systems, which are based on the principle of ultrasound and are widely used in navigation and aviation, and can be used to detect obstacles in front of them. There are also many similar applications, such as ultrasonic flaw detectors that specialize in detecting the production of precision parts on the surface.

The second field is ultrasonic processing, which is realized by the powerful energy of ultrasound, such as the use of ultrasonic cleaning glasses, dust removal in factories, ultrasonic welding, etc., which rely on ultrasound strong vibration is completed.