Physics Demo Number: 075

Approximate Run Time: 5 min

Doppler Shift Whistle (Hi-Tech Version)

Demo Description

An electronic whistle at the end of a rotating beam presents a sound that changes in frequency during approach towards and retreat from classroom observers during each rotation.

Scientific Principles

• Shifts in frequency occur for sound sources moving relatively to the observer.

Equipment

Rotating Beam with whistle

Equipment Location

• The whistle and rotating-beam holding structure reside in [E-1-5].

Instructions

 It would be best to come in and practice with the apparatus to gain familiarity with the mechanics of rotating the beam above your head without damaging anyone or anything.

 One also needs to learn to control the various switches which define the times at which the whistle emits sounds during the course of its revolving excursions .

Writeup created by David A. Burba

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