[DEMONSTRATION] - Parametric Excitation

Several different types of driving mechanisms can excite and maintain the motion of an oscillator. The standard mechanism is a direct drive, where an oscillating force is exerted on the mass. Another mechanism, which is seldom taught in classes, is parametric excitation. This mechanism has fundamentally different properties than those of a direct drive. We first demonstrate the parametric excitation of a simple pendulum in two different ways: by modulating the length of the pendulum, and by modulating gravity. We then demonstrate the cases a toy called a “clacker,” a rod pendulum, and a large spinning button.
Supports the following NPS courses: PH3119 (Oscillation and Waves), PH3451 (Fundamental Acoustics), PH4454 (Sonar Transduction).