Purpose:Show that a wave will be partially reflected at a point where the impedance changes.
The Shive Wave Machine illustrates transverse waves traveling down a torsional wire. Partial reflection can be produced by
• linking the two different segments as shown in the photograph,
• adding weights to the end of a central crossarm to produce an impedance glitch, or
• attaching the dashpot at a central location and adjusting it for partial absorption of the incoming wave.
Changing the arm mass changes the impedance of the medium. This changes the transmission speed; and when a wave passes through the junction, it may be partially reflected. Like a reflection from a free or fixed end (G3-03), this partial reflection can also be upright or inverted. Passing from higher to lower impedance gives an upright partial reflection; passing from lower to higher impedance gives an inverted partial reflection.