Power refers to how much work an object does in a unit of time, that is, power is a physical quantity that describes how fast the work is done. The amount of work is fixed, the shorter the time, the greater the power value. The formula for finding power is: power = work/time. Power characterizes the physical quantity of the work speed. The work done in a unit of time is called power and is denoted by P.
In the process of sound wave transmission, when the sound wave is transmitted to the originally 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 the sound waves enable the medium to obtain vibrational kinetic energy and deformation potential energy. The acoustic energy obtained by the medium due to sound wave disturbance is the sum of vibration kinetic energy and deformation potential energy.
As the propagation of sound waves in the medium is accompanied by the propagation of energy, if we take a tiny volume element (dV) in the sound field, let the original volume of the medium be Vo, the pressure be po, and the density be ρ0. The kinetic energy of the volume element (dV) due to sound wave vibration △Ek; △Ek=(ρ0 Vo)u2 /2
△Ek is kinetic energy, J; u is particle velocity, m/s; ρ0 is medium density, kg/m3; Vo is original volume, m3.
An important feature of ultrasound is its power. Superwave has much more powerful power 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 the ultrasonic waves, and the vibration frequency is the same as the frequency of the ultrasonic waves. The frequency of the vibration of the medium molecules determines the vibration speed. The higher the frequency, the greater the speed. In addition to the mass of the medium molecule, the energy obtained by the vibration of the medium molecule is also proportional to the square of the vibration speed of the medium molecule. Therefore, the higher the frequency of ultrasonic waves, the higher the energy obtained by the medium molecules. The frequency of ultrasonic waves is much higher than the frequency of ordinary sound waves, so ultrasonic waves can make the medium molecules get a lot of energy, but the effect of ordinary sound waves on the medium molecules is very small. In other words, ultrasound has much more energy than sound waves, and can supply enough energy to the medium molecules.