Come up with a way to measure the speed of sound, the simpler the better, the more accurate the bett

If you know the distance, you can find it out by using the echo and by measuring the time.

Such experiments must be performed at a large enough distance, otherwise it is difficult to guarantee accuracy.

The experimental principle of sound velocity measurement, because ultrasonic waves have the advantages of short wavelength, easy directional emission and easy reflection.

Because ultrasonic waves have the advantages of short wavelength, they are easy to be emitted and reflected. The advantage of measuring the speed of sound in the ultrasonic band is that the wavelength of the ultrasonic wave is short, and the speed of sound can be measured more accurately at short distances.

The emission and reception of ultrasonic waves are generally realized through the mutual conversion of electromagnetic vibration and mechanical vibration, and the most common method is to use the piezoelectric effect and the magnetostrictive effect to achieve. In this experiment, a transducer (probe) made of piezoelectric ceramics is used, which can be used to convert energy between mechanical vibration and alternating voltage in both directions.

One of the simplest and most effective ways to measure the speed of sound is to use the basic relationship between the speed of sound v, the frequency f and the wavelength, that is, a pair of ultrasonic piezoelectric ceramic transducers with the same structure (transmitter and receiver) are used to convert the sound pressure to the voltage.

The amplitude and phase of the ultrasonic wave are observed by using an oscilloscope, the wavelength is determined by the amplitude method and the phase method, and the frequency f is directly read out by the oscilloscope.

Resonant frequency: The ultrasonic piezoelectric ceramic transducer is the key component of the experiment, each pair of ultrasonic piezoelectric ceramic transducers has its own inherent resonant frequency, when the working frequency of the transducer system is in the resonant state, the ultrasonic power emitted by the transmitter is the largest, which is the best working state.

Fundamental quantities in acoustics.

In acoustics, it is the basic quantity in acoustics that describes the characteristics of a sound source and the sound field it generates, or some quantities that play a dominant role in certain acoustic phenomena and effects. Table 1 lists these fundamentals and their interrelationships. Of the first four quantities, sound intensity is the easiest to measure and can be measured very accurately, and the other three can be derived from sound intensity, so it has been mistaken in the past that only sound intensity is the fundamental quantity in acoustics.

The above content refers to: Encyclopedia - Acoustic Measurement.

The speed of sound was measured as follows: Experimental method - Echoes are often heard when singing or shouting in front of high walls or in valleys, and echoes are clearest and loudest in the morning, so this experiment is best carried out in the morning. First of all, choose a suitable experimental site, such as a high wall, with a flat and empty front of the high wall.

The experimenter stands at a distance of r from the high wall and beats the bangs at uniform intervals.

When the first bang sound is heard and the second bang sound is completely overlapped, it means that the time of each bang sound transmitted to the high wall and reflected by the high wall to the experimenter is exactly equal to the time interval t of the bang. Therefore, the velocity of sound propagation v is v=2r t.

Stand at a distance of 100 meters or more from the high wall and bang on the bangs at regular intervals. Take care to control the beat of the bangs so that the bangs reflected off the high walls overlap with the sounds. One of the students standing next to them will report the number of strokes, and the other students will use a stopwatch or watch to time them at the same time.

The time interval t between 20 and 50 strokes was measured, and the time interval t (seconds) of the knock was calculated from the obtained results.

Use a tape measure to measure the distance r (m) from the striking point to the high wall. Substituting the obtained data into the formula v=2r t to obtain the speed of sound vm. Also make a note of the temperature of the air at the time of measurement, as the speed at which sound travels in the air is related to the temperature.

Required [instruments and equipment] bangzi, stopwatch or watch, tape measure.

Precautions] The distance between the experimenter and the wall should be so that the echo can be heard clearly. If every other time a percussion is heard that coincides with an echo, then the formula for the speed of sound v=2r t. Experiment content:

Connect the measuring system. The output of the function signal generator is connected in parallel with the x(y2) input of the transmitting transducer and the oscilloscope, and the output of the receiving transducer is connected to the y1 input of the oscilloscope.

Adjust the resonant frequency. The signal generator outputs a sinusoidal signal, and the frequency is adjusted to the resonant frequency of the transducer, and the resonant frequency f is noted. At this time, the ultrasound emitted by the transducer is the strongest.

The speed of sound is measured using the standing wave method. The output frequency of the signal generator is at the resonant frequency; The operating mode of the oscilloscope is to select the switch to Y1, and the "pull Y1 (X)" knob is advanced. Start with the two transducers about 1cm apart, move the receiving transducer from near and far, observe the change of the received signal on the oscilloscope, and write down the 、...The 20 positions of the receiving transducer when the sine wave maximum is present are the vernier caliper readings L1, L2, L3, 、......l20。

The velocity of sound is measured using the phase comparison method. The output frequency of the signal generator is at the resonant frequency; The oscilloscope's Y-axis operating mode selector switch can be placed in any position, and the "pull Y1(X)" knob is pulled out.

Start with the two transducers about 1 cm apart, move the receiving transducer from near and far, observe the changes in the Lissajou pattern on the oscilloscope, and write down the 、...The 20 positions of the receiving transducer when a straight line occurs, i.e., the vernier caliper readings L1, L2, L3, 、......l20。

The wavelength is obtained by the difference-by-difference method, and then the speed of sound v is obtained. The uncertainty of the sound velocity is calculated, which represents the measurement result.

Methods for measuring the speed of sound:

Once a sound is generated, it doesn't reach your ears right away, usually after a while. It's hard to understand unless you have this experience yourself.

For example, if you attend a sports day and sit at a distance from the person who fired the gun, you will see the gun smoke first and hear the gunfire later. This is because light travels very fast (about 300,000 kilometers in 1 second) and sound travels much slower (about 340 meters in 1 second).

So you'll see the gun smoke right away, but the sound won't be heard until a little while.

The speed of sound is the speed of propagation of a weak pressure disturbance in a medium, and its magnitude varies depending on the nature and state of the medium. The speed of sound in the air is about 1 m s at 15 standard atmospheres and 340 m.

In the measurement of sound velocity, what methods are used to measure the key of the potato ().

a.Simulation and induction.

b.Compensating method and resonance interferometry.

c.Phase comparison method and time difference method.

d.Phase comparison of the digital method and the compensation method.

Correct answer: Phase comparison method and time difference method.

Methods for measuring sound velocity include:

Direct method: The speed of sound is calculated by experimentally measuring the travel time and distance of sound through the air.

Resonance method: Resonance is generated in a pipe, the resonance frequency is measured, and the speed of sound is calculated from the wavelength and frequency.

Astronomical method: Calculate the speed of sound by observing the time difference of sound propagating in the atmosphere, such as observing lightning and thunder.

Merkel's method: The relationship between the resonant frequency of a cylinder and the speed of sound is used to measure the speed of sound.

Doppler effect: The Doppler effect is used to measure the speed of sound, that is, to measure the frequency change of sound waves in moving air.

Electromagnetic method: The velocity of sound is measured using the relationship between the velocity of a sound wave as it travels along a magnetic field and the velocity of an electromagnetic wave.

Similarities: Both are measured with continuous waves, both rely on an oscilloscope.

Difference: Resonance method: The sound waves propagating in parallel interfere with the reflected waves to form standing waves. Changing the propagation distance of half a wavelength, the amplitude of the standing wave changes by one period, so that the wavelength can be measured, multiplied by the frequency, and the speed of sound is obtained.

Phase method: Compare the phase difference between the relative and transmitted waves of the received wave, change the propagation path of a wavelength, and change the phase by 360 degrees, so as to view the phase diagram by measurement.

The wavelength can be measured, multiplied by the frequency, and the speed of sound can be obtained.