DEMONSTRATING DIFFERENT FORMS OF THE BENT TUNING CURVE WITH A MECHANICAL OSCILLATOR

A mechanical rotating oscillator is used to demonstrate different bent tuning curves with basically the same system. A softening restoring f orce is realized by operating the oscillator as a gravitational pendul um. A hardening restoring force is realized by a spring acting on the oscillator. Tuning curves which are bent either to the right or to the left, as well as bistability and the jump effect, can be demonstrated . Furthermore, a doubly bent curve of amplitude versus frequency is sh own to exist which gives rise to a doubly bent tuning curve and trista bility. The experiments are a good introduction to unexpected phenomen a related to nonlinear physics.