I am working on a project concerned with sonoluminescence,in which we have to create standing ultrasonic waves in water inside a 250cc flask. Testing the piezoceramics I encountered with two problems:
- The amplitude of the waves, which have been propagated to the water (detected by a microphone), differs when I change the pole of the ceramic that contacts with the flask, i.e. when (-) pole is connected to the flask, the amplitude is so much lower than the connection of (+) pole of the ceramic to the flask.
- The resonance frequency differs for the connection of (-) and (+) poles to the flask as described above, e.g. for (-) pole it resonates at around 21200Hz, but for (+) pole it happens at about 21500Hz. Please let me know if this behavior is natural or not. Also please explain what I can do for solving the problem.