PURPOSE: To illustrate longitudinal standing waves in an aluminum rod.
DESCRIPTION: Apply powdered rosin to your fingers and stroke the aluminum
rod firmly while holding it at a nodal point. Holding the rod precisley in the center
produces the fundamental. Holding the rod at 1/4 of the way from one end produces
the second harmonic, holding at 1/6 of the way from one end produces the third harmonic,
etc.
The rod is an ordinary aluminum rod about 4 ft long. The speed of sound in
aluminum is about 16,700 ft/sec. The sound is very loud and lasts a long time.
The Q for this system is very high, around 100,000!
Practice is required.
EQUIPMENT: as photographed.
Updated by Jun Qi in 4/5/2000