Experimental device for measuring solid audio frequency sound velocity

Abstract

The invention relates to a solid audio frequency sound speed testing experimental device, which is formed by a solid bar, a brace, a piezoelectric transducer, a change-over switch set, a testing box and a moving testing clip. It is characterized in that the piezoelectric transducers are separately fixed on the two ends of the solid bar of the brace; when one of the change-over switch set presses the measuring key, the single chip microcomputer generates a single impulse and opens the timer; the single impulse uses the photocoupler to drive the piezoelectric transducer on one end of the solid bar to generate the sound frequency vibration, then the sound frequency vibration is transited to the piezoelectric transducer on the other end by the solid bar to generate the voltage, which is amplified, shaping pulsed and sent to the single chip microcomputer by the photocoupler which can stop the timer and display the transiting time of the sound frequency vibration on timer display. The change-over switch set can change-over various material solid bars to do measuring.

Description

Technical field [0001] The invention relates to an experimental device for studying the retransmission speed of sound waves in solid materials, which is used for general physics experiments in universities, middle school physics experiments and demonstrations. Background technique [0002] Sound waves are mechanical waves that propagate in elastic media. [0003] The relationship between the velocity (v) of a plane longitudinal wave propagating in an elastic medium and the density (ρ) of the medium and Young's modulus of elasticity (E) is as follows: [0004] v = E / ρ [0005] Sound waves have different speeds in different media. The speed of propagation in solid materials is several to ten times faster than air (differences between different materials), for example: the speed of sound in air (15°C) is about 340 m / s, and the speed of sound in aluminum rods is about 5150 m / s. The measurement of the ...

AI Technical Summary

Problems solved by technology

[0011] Use the "standing wave method" and "phase method" to measure the speed of sound, and use an oscilloscope to measure the peak, valley or phase between waves of the standing wave. The reading error is large and unstable.

[0012] The "time difference method" is more accurate and intuitive, but it is difficult to apply

[0013] For example, a foreign company demonstrates the experimental device. It uses a hand-held small iron rod to strike one end of the long iron rod to generate vibration, and then starts timing. The weight and position are different, the intensity and duration of the reflected wave of the sound wave in the long iron rod are different, the interference is measured correctly, and the measured data has a large error

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