PURPOSE: To show how wave fronts crowd together in front of and spread out behind a moving source.
DESCRIPTION: The single point source can be moved by rotating the support arm in the photograph. Moving the source uniformly in one direction demonstrates the Doppler effect in a clear and understandable way.
REFERENCES: (PIRA unavailable.) Several good film loops and movies can be used which show ripple tank effects very clearly.
EQUIPMENT: Ripple tank with accessories on cart.
SETUP TIME: 5 min.
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