Vernier Software and Technology
Vernier Software & Technology

Doppler Effect: Sound Waves

Introduction

Have you ever noticed that if a car with a horn blowing is moving past you rapidly that the sound waves emitted by the horn seems to change frequency? In 1842 an Austrian physicist, Hans Christian Doppler, observed and analyzed the same phenomenon for sound emitted by a passing train. Hence the phenomenon is known as the Doppler Effect.

A similar effect is found for the propagation of light and other electromagnetic waves from moving sources. In fact highway patrol officers use radar to measure Doppler shifts in radio waves so they can determine how fast vehicles are moving.

In this activity, you will work with movies of a honking car moving fairly rapidly on a straight level road past a stationary microphone.

Objectives

In this activity, you will

  • Verify that the Doppler Equations can be used to predict the ratio (fF / fB) of the apparent car horn frequencies before and after the car passes the microphone.

Software for Experiment

This experiment uses Logger Pro software for video analysis. The video for analysis is included with the lab book.

Standards Correlations

No standards correlations for this experiment.

Experiment 23 from Physics with Video Analysis Lab Book

<em>Physics with Video Analysis</em> book cover

Included in the Lab Book

Vernier lab books include word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.

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