Doppler Effect Applet
This applet lets you interactively experience the Doppler Effect. By
experimenting with this applet, we hope that you will get a better
understanding of what the Doppler Effect actually is. Thanks to this hands-on
opportunity, you can learn by seeing, hearing, and reading about the Doppler
To start you off, we are going to walk you through your first run with the
- Position the human figure anywhere in front of the plane.
- Click on the sound button to hear the plane.
- Then, all you have to do is click "GO!" to see and hear the Doppler Effect in
- You should detect a rise in pitch as the plane nears the figure, then you'll hear it
lower as it passes the figure. That is the Doppler Effect!
The speed of the airplane is posted in the bottom left-hand corner of the top
Click on the screen in the bottom right to see the sound wave that the plane
is emitting. Watch the frequency of the wave increase (you will see the wave become more "compressed") as the plane
flies over the figure, then decrease (the wave will stretch horizontally) as it gets further away from
the figure. You can also watch the amplitude of the wave. The closer the plane is to the figure, the greater the amplitude will be, and thus the louder the sound will be.|
Under "Plane Speed" you can select the speed of the plane. 330 mph is
approximately half the speed of sound. 660 mph is about the speed of sound, or
Mach 1. Every 330 mph will be another half of the speed of sound. If the plane travels faster than or at the speed of sound, you will hear a sonic boom when the shokwave passes by the person. The first time this happens, you may experience a small delay as the sound loads. This will only happen once.|
You can move the figure while the plane is moving to further explore the
The first P icon below links back to information on the Doppler Effect; the second link to information on the speed of sound.