Introduction

No doubt you have experienced how the pitch of a car horn or siren changes as it approaches and then passes you. Because study of this effect with sound waves is difficult to visualize, one typically examines the Doppler effect with water waves in a ripple tank. Measurements of frequency and wavelength are easier to make, and changes in the waves due to the motion of the source are easier to observe. In this experiment, you will develop a causal model to account for the change in pitch and an expression relating the shifted frequency to the speed of the object and of the wave in the medium.

Objectives