The Difference Between Ultrasonic Frequency And Power

Introduction to Ultrasonic Frequency:

The frequency of ultrasound is the number of times it completes periodic changes per unit of time, and is a quantity that describes the frequency of periodic motion. It is commonly represented by the symbol f, with the unit being one second and the symbol s-1. In commemoration of the contribution of German physicist Hertz, the unit of frequency is named Hertz, abbreviated as "Hz", with the symbol Hz. Every object has a frequency determined by its own properties that is independent of amplitude, called the natural frequency. The concept of frequency is not only applied in mechanics and acoustics, but also commonly used in electromagnetics, optics, and radio technology.

The time required for a particle in a medium to oscillate back and forth once at its equilibrium position is called a period, represented by T in seconds (s); The number of times a particle completes vibration within 1 second is called frequency, represented by f in cycles per second, also known as Hertz (Hz). The period and frequency are inversely proportional to each other, represented by the following equation: f=1/T

The relationship between the wavelength (λ) and frequency of ultrasonic waves in a medium is: c=λ f

In the formula, c is the speed of sound, m/s； λ is wavelength, m; f is frequency, Hz.

From this, it can be seen that for a certain medium, the propagation speed of ultrasound is constant. The higher the frequency of ultrasound, the shorter the wavelength; conversely, the lower the frequency of ultrasound, the longer the wavelength.

Introduction to Ultrasonic Power:

The power of ultrasound refers to the amount of work done by an object per unit time, which is a physical quantity that describes the speed of work done. The amount of work is constant, and the shorter the time, the greater the power value. The formula for calculating power is: power=work/time. Power is a physical quantity that characterizes the speed of work done. The work done per unit of time is called power, represented by P.

In the process of ultrasonic transmission, when ultrasonic waves are transmitted to a previously stationary medium, the medium particles vibrate back and forth near the equilibrium position, causing compression and expansion in the medium. It can be considered that ultrasound enables the medium to acquire vibrational kinetic energy and deformation potential energy. The acoustic energy obtained by the medium due to ultrasonic disturbance is the sum of vibrational kinetic energy and deformation potential energy.

As ultrasound propagates in a medium, energy also propagates. If we take a small volume element (dV) in the acoustic field, let the original volume of the medium be Vo, the pressure be po, and the density be ρ 0. The volume element (dV) obtains kinetic energy △ Ek due to ultrasonic vibration; △ Ek=(ρ 0 Vo) u2/2

Δ Ek is kinetic energy, J; u is particle velocity, m/s； ρ 0 is the density of the medium, kg/m3； Vo is the original volume, m3.

One important characteristic of ultrasound is its power, which is much stronger than ordinary sound waves. This is one of the important reasons why ultrasound can be widely used in many fields.

When ultrasonic waves reach a certain medium, the molecules of the medium vibrate due to the action of ultrasonic waves, and their vibration frequency is the same as that of ultrasonic waves. The frequency of the vibration of the medium molecules determines the speed of the vibration, and the higher the frequency, the greater the speed. The energy obtained by a medium molecule due to vibration is not only related to the mass of the medium molecule, but also proportional to the square of the vibration velocity of the medium molecule. So, the higher the frequency of ultrasound, the higher the energy obtained by the medium molecules. The frequency of ultrasound is much higher than that of ordinary sound waves, so ultrasound can give medium molecules a lot of energy, while ordinary sound waves have little effect on medium molecules. In other words, ultrasound has much greater energy than sound waves and can provide sufficient energy to medium molecules.

The difference in frequency and power of ultrasonic:

The frequency and power of ultrasound are two key parameters for measuring its performance. Macroscopically, power determines the intensity and penetration ability of ultrasound, while frequency determines the penetration depth and resolution of ultrasound.

The higher the frequency, the shorter the wavelength, and the stronger the penetration, but the greater the power, the stronger the sound energy can be generated. In applications, ultrasound used in the medical field is mainly low-power and high-frequency, which can be used for ultrasound examination and treatment; The ultrasonic waves used in the industrial field are mainly high-power and high-frequency, which can be used for processing, cleaning, measurement, etc. The frequency and power of ultrasound are two key indicators of ultrasound performance. Choosing appropriate ultrasonic parameters can better meet application requirements.