PURPOSE: To demonstrate branching and recombining with two wave machines in parallel.

DESCRIPTION: This is the mechanical equivalent of the Quincke tube interference demonstration for sound (H2-25) or of a parallel LC circuit. At the first connecting point the amplitude and phase are directly coupled (i. e., the same) and waves continue down both machines. Due to the different wave velocities in the two machines, when the transmitted waves arrive at the second coupling they may be out of phase. If they arrive 180 degrees out of phase a node is created and no further energy is transmitted. In analogy with pinching one of the Quincke's tubes, one of the connectors can be removed to allow energy to pass. Crossarm weights are used to counterbalance the alligator crossarm connectors.

SUGGESTIONS: See Demonstration Reference File for sample data.

REFERENCES: (PIRA 3B22.30)See Demonstration Reference File for further information and experiments.

EQUIPMENT: Two Shive Wave Machine segments, 2 large support blocks, 2 alligator crossarm connectors, 2 brass crossarm counterweights, and wave generator.


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