PURPOSE: To demonstrate the traveling waves and/or the
standing waves of a discrete mechanical system with 72 oscillators.
DESCRIPTION: A wave machine consists of a discrete sequence of
oscillators connected by a wire. There are 72 rods of equal length. The wire that
connects the rods can twist to produce a torsional wave. A traveling wave is
produced by moving the spines at one end of the machine up and down with your hand. Vary
the amplitude and the frequency of the traveling wave pulse and observe that the wave
speed is the same for all amplitudes and all frequencies. The reflection at the end
can be fixed or free to produce inverted or non-inverted reflections, or it can be damped
to produce no reflection.
A mechanical vibrator can be used to produce standing waves. The sequence of harmonics for the modes of vibration of a discrete system can be shown. The end can be fixed or free. The nodes and anti-nodes for each mode can be clearly seen. A blacklight can be used to illuminate the glow paint at the tips of the rods.
EQUIPMENT: Wave machine, either with or without blacklights, and with or without the end clamp, as photographed.
SETUP NOTES: As shown in the photo below at right you can use blacklights. Or, as shown in the photo at left, you can use this without blacklights.
Updated by Jun Qi in 3/24/2000
