Calculate the shift in frequency for a moving source or observer.
Doppler Parameters
Hz
m/s
m/s
Positive = Towards Observer
m/s
Positive = Towards Source
Calculation Results
Enter frequency and velocities
About this calculator
Quick Reference
f₀Source Frequency
vSpeed of wave in medium
v_oVelocity of observer relative to medium
v_sVelocity of source relative to medium
Overview
The Doppler effect is the change in frequency of a wave in relation to an observer who is moving relative to the wave source. Common examples include the changing pitch of a siren as it passes or the red-shift of distant stars.
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Pro Tips
Velocity inputs: Use positive (+) for moving TOWARDS the other object, and negative (-) for moving AWAY.
Wave Speed (v) for sound in air is approximately 343 m/s.
If the source moves faster than the wave speed (v_s > v), a sonic boom (shock wave) occurs.
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Fun Facts
"Astronomers use the Doppler effect (redshift/blueshift) to determine if stars and galaxies are moving toward or away from Earth."
"Police radar guns use the Doppler effect to measure the speed of cars by bouncing radio waves off them."
"Bats use the Doppler effect while echolocating to determine the velocity of their prey."
