W.2.14 Doppler Shift

Doppler shift for sound is dramatically demonstrated by swinging a ringing tuning fork around your head.

A sponge ball with a central whistle is also available. Students can experience the doppler shift of sound first hand by throwing the ball around the lecture hall.

Doppler shift of a car horn at 30 MPH. The link is http://www.exploratorium.com/imagery/sounds/30_MPH_doppler.au

The animated applet below is a good way to visualize the doppler shift. Click on the run button. You can control the speed of the source. The applet is also available on our ephysics site.

The picture below shows boat wakes which occur when the boat moves faster than the speed of water waves. Compare this to the ephysics applet when the source moves faster than the speed of sound.