What is resonant frequency?
Date: Around 1993
What is resonant frequency? Does every material have a resonant
frequency? What are the implications of a resonant frequency?
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.
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Update: June 2012