Piezoelectric Problems?

Question

Does anyone know these things about Piezoelectricity?

1) If you want to see the effects of Piezoelectric crystals, should you place them them in a circuit (between two piece of wire, connected to an ammeter. Then, place a lot of force on the Piezoelectric crystal, and see what the ammeter reports? Or will that not work? Thanks.

2) A Piezoelectric crystal generates electricity when something strikes it, right? But the electricity needs to be conducted through the crystal, right? So is there the faintest possibility that changing the temperature will change the amount of current (like in conductor's resistances)?

THANKS!

Answer 1

1) Not an ammeter; an oscilloscope is best. The PE crystal displaces a certain small charge while it is being deformed by a force. It will generate a pulse when it deforms and an opposite-polarity pulse when it recovers its original shape. It's a high-impedance source which means it outputs considerable voltage but negligible current. It only produces this current while changing shape, so an impact will produce a pair of short pulses most easily displayed on an oscilloscope.
2) Since its output is a charge displacement, it acts pretty much like a capacitor, and its output won't change significantly with temperature.