Beaker is broken by sound from speaker.

Glass broken by sound at resonant frequency. An audio oscillator and power amplifier are used to drive a heavy-duty speaker. The glassware is positioned on a rotating pedestal in front of the speaker. Resonance is found using a microphone and oscilloscope and is typically around 850Hz. If using a beaker, maximum resonance is found with the spout at +/- 30 degrees from the speaker. This display can also be projected for the class to see if desired. After the resonant frequency is found the amplitude can be turned up, causing the oscillation of the glass to exceed its elastic limit and thus to shatter. The motion of the glass can be nicely seen using a stroboscope, and may be displayed for a large group using the TV camera mounted directly above the glass.