Vibrational frequency of Piezoelectric effect

[ralden]

when a piezoelectric material experience a stress it generates voltage, and also when you applied voltage the piezo-material experience a vibrational frequency. Using oscilloscope we can determine the induced frequency of the piezo-material with respect to the applied voltage. Now given the dimensions of the material we can also determine the resonant/normal frequency of the material. My question is what is the frequency that detected by oscilloscope when you applied a voltage? is it the resonant frequency? or other form of frequency? then if so what is the relation of that detected frequency to the voltage and resonant frequency?

 

[tech99]

when a piezoelectric material experience a stress it generates voltage, and also when you applied voltage the piezo-material experience a vibrational frequency. Using oscilloscope we can determine the induced frequency of the piezo-material with respect to the applied voltage. Now given the dimensions of the material we can also determine the resonant/normal frequency of the material. My question is what is the frequency that detected by oscilloscope when you applied a voltage? is it the resonant frequency? or other form of frequency? then if so what is the relation of that detected frequency to the voltage and resonant frequency?

A typical piezo resonator is the quartz crystal. It behaves primarily like a very efficient series resonant LC circuit. Away from the resonant frequency it has high impedance, and at resonance it has low impedance. So if you excite the electrodes of the crystal with variable frequency coming from a signal generator, and measure the voltage across the plates with a CRO, there will be a sharp dip in voltage at resonance.
In practice there is also a nearby parallel resonance which arises from the capacitance of the electrodes in parallel with the reactance of the crystal, and a number of resonances arising from different mode of vibration.