Oscillations
and Waves > Instruments > Air Columns
DCS#
3D30.xx
ACOUSTIC LASER
APPARATUS
acoustic laser
202-07-D4
5 A power supply
202-08-D
DESCRIPTION
Turn the power supply up to about 4
A to
heat the nichrome wire. The ceramic stack impedes
the flow of
hot
air along the tube and the resulting temperature (and pressure)
gradient sets up
standing waves in the air column, causing the tube to sing.
The frequency is that of the fundamental mode of the test tube.
You can show this by blowing across an identical test tube without the
heating element inside. The paper sleeve allows you to change the
pitch.
NOTES
Use caution with the hot test tube.
We have a 22" x 1" test tube that
produces a lower note but stops after a short time.
