Calculateur de l'Effet Doppler Gratuit
Calculez le décalage de fréquence dû à l'effet Doppler pour les sources sonores en mouvement.
Observed Frequency
482.17 Hz
Observed Frequency vs Source Frequency
Formule
Doppler Effect
The Doppler effect is the change in observed frequency caused by relative motion between source and observer.
Formula
f_obs = f_source * (v_sound + v_observer) / (v_sound - v_source)
Sign convention: speeds are positive when source and observer move toward each other.
Exemple Résolu
An ambulance siren at 440 Hz approaches a stationary observer at 30 m/s.
- 01f_obs = f_s * (v + v_o) / (v - v_s)
- 02f_obs = 440 * (343 + 0) / (343 - 30)
- 03f_obs = 440 * 343 / 313
- 04f_obs = 482.2 Hz
Questions Fréquentes
Why does a siren sound higher-pitched as it approaches?
The sound waves are compressed in front of the moving source, shortening the wavelength and increasing the observed frequency.
Does the Doppler effect apply to light?
Yes, but the relativistic Doppler formula must be used for light since light speed is constant in all reference frames.
What happens when source speed equals the speed of sound?
The denominator becomes zero, meaning infinite observed frequency. This corresponds to a sonic boom (shock wave).
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