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Music and Standing Waves
Name: Sriram S.
Status: student
Age: 15
Location: N/A
Country: N/A
Date: 2000-2001
Question:
we say that a standing wave pattern is formed along the
length of a FLUTE.
we also say that energy is not transported to the left or right in a
standing wave.
are these two statements contradictory? if not, what do they actually mean
that energy in standing wave is "standing" as we can hear the musical
notes from a FLUTE.
Replies:
Sriram,
A flute vibrates when blown. Before anything has a chance to begin, nothing
is vibrating. As the air from your mouth hits the "mouthpiece end" of the
flute, some energy is transferred to the flute itself. This sends some
vibration down the length of the flute. At the far end, there is nowhere
for the energy to go, so it reflects back up toward the mouthpiece. In a
very short time, amount of energy going down the flute (as a wave) is
balanced by the amount coming back up (another wave). This balance has the
effect of producing a standing wave. If there were no air molecules outside
the flute, this energy would bounce back and forth almost forever.
Because the vibrating sides of the flute smash into air molecules, some
energy gets transferred to the air around the flute. It is not in the
direction of the flute's standing wave (up or down the length of the flute).
The air near the flute is made to vibrate at the frequency of the flute
itself. These air molecules then smash into neighboring air molecules, and
you have a sound wave carrying energy to your ears.
Dr. Ken Mellendorf
Illinois Central College
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