Electric Resonance

Resonance is a general phenomenon that occurs in any system possessing a natural tendency to oscillate at some particular characteristic frequency, called its natural (or resonant) frequency. When such a system is driven by an external, periodically-varying source whose OWN frequency happens to match this natural frequency exactly, the resulting oscillations build up to an unusually large amplitude -- this dramatic amplitude buildup, specifically at the matching frequency, is what defines resonance. Everyday examples include a glass shattering when a musical note at exactly its own natural frequency is sustained loudly enough, and a radio receiver 'picking out' one particular broadcasting station from among the many different frequencies simultaneously present at its antenna. …