# Crystal Voltage Measurement

The above is an excerpt from the book "Crystal Oscillator Circuits". It said it is meaningless to measure voltage across a crystal. I can not understand why. When crystal is operating in parallel resonance region, it appears inductive. And everyday voltmeter can not calculate $$\frac {dI}{dt}$$ Which is necessary to calculate the voltage across inductor. Is this the reason why the excerpt above claimed that it is meaningless to calculate voltage across a crystal?

• The voltage measured across a crystal is not meaningless in general - that quote reads "is meaningless as a measure of current through the crystal" - probably because you don't know the impedance of the crystal when it's slightly off resonance, so can't use I=V/Z to calculate current from the measured voltage. – brhans Nov 6 '17 at 16:09