Doppler Effect Receding Source Calculator
What is the Doppler Effect Receding Source Calculator?
The Doppler Effect Receding Source Calculator is a tool used to determine the observed frequency of a wave (such as sound or light) when the source of the wave is moving away from the observer.
Why use it?
- To predict how sound or electromagnetic waves behave when the source moves away.
- Used in radar technology, astronomy, medical ultrasound, and speed detection.
- Helps analyze motion of objects emitting waves, such as stars, sirens, or vehicles.
How does it work?
The calculator uses the Doppler Effect formula for a receding source:

Since the source is moving away, the denominator increases, resulting in a lower observed frequency (the wave is stretched out).
When is it used?
- When analyzing the drop in pitch of a siren as an ambulance drives away.
- In astronomy, to detect redshift in light from distant galaxies.
- In Doppler radar, to track objects moving away.
- In medical imaging, for ultrasound Doppler scans.