Oscillations and Waves

First published: 1963

Brief summary

Feynman Lectures chapter introducing oscillatory systems.

Article

A driven harmonic oscillator is acted on by a periodic external force in addition to its restoring force and damping. After transient motion decays, the system approaches a steady oscillation at the frequency of the driving force.

The amplitude and phase of the steady response depend on driving frequency. At low frequency the oscillator follows the force nearly in phase, while at high frequency its response becomes small and increasingly out of phase.

Near the natural frequency, energy transfer from the driver becomes especially effective and the response reaches a maximum. Damping prevents unlimited growth and shifts and broadens the resonance curve.

The analysis of a driven oscillator provides a model for mechanical vibration, electrical circuits, acoustics and many other linear systems. It shows how natural frequency, forcing and energy loss jointly determine the observed motion.

Source details and credits

• Source / publisher: Caltech
• Source type: Textbook chapter
• URL type: WWW
• Credits: Caltech
• URL: https://www.feynmanlectures.caltech.edu/I_23.html