Oscillations
and Waves > Instruments > Air Columns > Organ Pipes
DCS# 3D32.xx
END CORRECTIONS
AND
MODE SWITCHING IN ORGAN PIPES
APPARATUS
organ pipe
202-05
end
correction thing
202-07-C
nitrogen
cylinder/regulator/tubing
201A
DESCRIPTION
Show first that we can get three
modes, at
expected musical intervals, and four with pipe closed (close it by
pushing
down hard on a closed part of the sponge rubber surface).
With just enough air pressure to
operate pipe
in the first open mode, press it down over successively smaller holes
to
hear the pitch get progressively more flat. With smallest hole,
you
have gone down nearly one octave, it is now nearly like a closed pipe.
Now raise pressure to highest value
which
will still allow open pipe to speak in first mode; as you move it to
smaller
holes it eventually jumps up a mode and goes up in pitch, as is
expected since edge tone frequency is above resonance frequency of
first
open mode.
