Doppler Effect Calculator
Calculate the observed frequency for moving sources and observers.
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Enter the source frequency, speed of sound, source speed, and observer speed. Select the direction of motion for both source and observer. The calculator shows the observed frequency, frequency shift, and observed wavelength.
About Doppler Effect
The Doppler effect, named after Christian Doppler who proposed it in 1842, describes the change in wave frequency due to relative motion between source and observer. For sound, the observed frequency depends on the speeds of both source and observer relative to the medium. When a source approaches, wavefronts compress and frequency increases. When it recedes, wavefronts stretch and frequency decreases. This effect is used in radar, medical ultrasound, and astronomical measurements.
Frequently Asked Questions
What is the Doppler effect?
The Doppler effect is the change in observed frequency of a wave when the source or observer moves relative to the medium. An approaching source sounds higher-pitched; a receding source sounds lower-pitched.
Does the Doppler effect apply to light?
Yes. The Doppler effect applies to all waves, including light. Red shift (lower frequency) indicates objects moving away, and blue shift indicates approach. Astronomers use this to measure star velocities.
What happens when the source exceeds the speed of sound?
When the source moves faster than sound, it creates a shock wave (sonic boom). The Doppler formula breaks down at and above the speed of sound for the approaching case.