Index Key:  PHY082
Author:     mon
Subject:    What is resonant frequency?
Text:       What is resonant frequency?  Does every material have a resonant 
frequency?  What are the implications of a resonant frequency?

Response #:  1 of 1
Author:      proach
Text:        Resonant frequency is observed in a wide variety of systems, from 
simple mechanical systems to complex electronics circuits.  But the resonant 
frequency is a property of the SYSTEM, not any material in it.  Take a simple 
resonant mechanical system:  a pendulum.  Its resonant frequency does not 
depend on the materials it is made of, or even on the mass of the pendulum 
weight.  It depends only on the length of the pendulum, and on the local 
acceleration of gravity.  Another simple system, a mass hanging from a spring, 
also has a resonant frequency.  Here the frequency depends on the mass and the 
spring, but not on the materials involved.  As these examples show, a resonant 
system generally involves a mass that can be displaced and a restoring force 
that is proportional to the displacement.  In electrical or acoustical 
systems, there are similar concepts involving some sort of mass or inertia and 
some sort of restoring force.  Every musical instrument, including your voice, 
depends on resonant frequencies.