Doppler Effect Simulator

The Doppler Effect: Waves in Motion

1. Why the Pitch Changes

Have you ever noticed how a police siren sounds higher-pitched as it rushes toward you and then suddenly drops in pitch as it passes? This is the Doppler Effect. It happens because the source of the sound is "catching up" to the waves it just sent out, bunching them together in front and stretching them out behind.

2. Compression and Rarefaction

In this simulation, watch the blue circles (the wave crests). When the source moves forward, the circles in front get closer together. Shorter distance between waves means a higher frequency (and higher pitch). Behind the source, the waves are farther apart, resulting in a lower frequency.

3. Breaking the Sound Barrier

If you set the speed to 100 or higher, you'll see something amazing: the source starts moving faster than its own waves. This is Supersonic travel. The waves bunch up into a single, massive V-shaped shockwave called a Mach Cone. In the real world, this is what causes a "Sonic Boom" when a jet flies faster than the speed of sound.

4. Beyond Sound

The Doppler effect isn't just for sound; it works for light too! When a star moves toward us, its light waves bunch up and look bluer (Blueshift). When it moves away, they stretch out and look redder (Redshift). This is how astronomers discovered that the entire universe is expanding!