Oscillations and Waves > Waves > Longitudinal Waves DCS# 3B20.70
CROVA'S DISK

APPARATUS
Crova's disk 202-17-E2
overhead projector 201

DESCRIPTION
Nonconcentric circles are printed on the transparent disk.  The opaque housing blocks from view all but a narrow slit.  When the disk is rotated, the projection looks like a longitudinal standing wave.

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NOTES
We also have a larger motor-driven version:  202-06-A

REFERENCE
Some history:
http://physics.kenyon.edu/EarlyApparatus/Rudolf_Koenig_Apparatus/Crovas_Disks/Crovas_Disks.html