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人的耳朵能感觉到的声音频率只是在每秒钟1.6—2万次振动的范围。但是在自然界和工程技术中发现有快得多的、我们不能听到的、叫做超声波的振动。它们的特性以及对各种对象和过程的作用的研究,引起了许多最有意义的科学发现,并为在物理学、化学、生物学和工程中广泛地应用超声波,创造了先决条件。在实验室中和工程实践中,作为超声波来源的,通常是用具有卓越特性的——压电的——晶体。假如这种晶体通以交流电压,那么它们就开始进行周期性的机械振动。并且振动的频率等于所用的电压。在这种情况下产生最强的超声波,就是在被通入的电压频率与压电的晶体本身的频率
People’s ears can feel the sound frequency is only 1.6-2 million times per second vibration range. But in nature and engineering, we find that much faster, we can not hear, what is called ultrasonic vibration. Their character and research on the role of various objects and processes has generated many of the most significant scientific discoveries and created the preconditions for the widespread application of ultrasound in physics, chemistry, biology and engineering. In laboratory and engineering practice, as a source of ultrasound, it is common to use piezoelectric ceramics with superior properties. If this crystal through the AC voltage, then they began to periodically mechanical vibration. And the frequency of vibration is equal to the voltage used. In this case produces the strongest ultrasound, is the frequency of the voltage being passed and the frequency of the piezoelectric crystal itself