The Difference Between Ultrasonic Frequency and Power

Introduction to ultrasonic frequency:

The frequency of ultrasound is the number of times a periodic change is completed per unit time, and it is a quantity that describes the frequency of periodic motion. It is commonly represented by the symbol f, with a unit of one second and a symbol of s-1. In commemoration of the contribution of German physicist Hertz, people named the unit of frequency Hertz, abbreviated as "Hertz", with the symbol Hz. Every object has a frequency independent of amplitude determined by its own properties, which is 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 the medium to oscillate back and forth at equilibrium position once is called the period, expressed in T, and measured in seconds (s); The number of times a particle completes its vibration within 1 second is called frequency, represented by f, in cycles per second, also known as Hertz (Hz). The period and frequency have a reciprocal relationship with each other, expressed as follows: f=1/T

The wavelength of ultrasound in the medium( λ) The relationship between frequency is: c= λ F

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

It can be seen that for a certain medium, the propagation speed of ultrasound in it 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 of time, that is, power is a physical quantity that describes the speed of work done. The amount of work is fixed, 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 time is called power, expressed in P.

During the process of ultrasound transmission, when ultrasound is transmitted to a previously stationary medium, it causes the particles of the medium to vibrate back and forth near the equilibrium position, resulting in compression and expansion in the medium. It can be said that ultrasound enables the medium to obtain vibrational kinetic energy and deformation potential energy. The sound energy obtained by the medium due to ultrasonic disturbance is the sum of vibration 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 sound field, let the original volume of the medium be Vo, the pressure be po, and the density be ρ 0 The kinetic energy Δ Ek obtained by the volume element (dV) due to ultrasonic vibration; △ Ek=( ρ 0 Vo) u2/2

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

One important characteristic of ultrasound is its power, which is much more powerful 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 the frequency of ultrasonic waves. The frequency of the molecular vibration of the medium determines the vibration speed, and the higher the frequency, the greater the speed. The energy obtained by medium molecules due to vibration is not only related to the mass of the medium molecules, but also directly proportional to the square of the vibration velocity of the medium molecules. 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 the medium molecules.

The difference between the frequency and power of ultrasound:

The frequency and power of ultrasound are two key parameters for measuring its performance. From a macro perspective, power determines the intensity and permeability of ultrasound, while frequency determines the depth and resolution of ultrasound penetration.

The higher the frequency, the shorter the wavelength, the stronger the penetration, but the greater the power, which can produce stronger sound energy. 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 ultrasound parameters can better meet application requirements.