PURPOSE: To illustrate resonance by trying to trick your students.

DESCRIPTION: When a group of people concentrate on one of the pendula, held as shown by the instructor, their psychoacoustic brain waves rapidly become in phase, producing enough mechanical energy to make only that pendulum oscillate. Although there may be alternative explanations of this device which make use of the concept of driven resonance, many people continue to believe that brain waves can cause this very startling effect.

You can make your own Psychoacoustic Vibration Transducer by following these simple instructions. (You will need Adobe Acrobat Reader to view these.)

SUGGESTIONS: Practice a bit. This device really blows away younger students.

REFERENCES: (PIRA unknown.)

EQUIPMENT: Psychoacoustic vibration transducer (left), and larger lecture-demonstration version (right), as photographed.

SETUP TIME: None.