Doppler Effect Calculator
Calculate the observed frequency shift when a sound source moves relative to an observer.
📣 Physics📐 f_obs = f × (v ± v_obs) / (v ∓ v_src)
Source frequency (Hz)
Speed of sound (m/s)
Source velocity (m/s)
Observer velocity (m/s)
Source direction
Please enter valid values.
Formula & Reference
| Variable | Formula | Units |
|---|---|---|
| Doppler Effect Calculator | f_obs = f × (v ± v_obs) / (v ∓ v_src) | Hz |
Step-by-Step Examples
Example 1
Ambulance Approaching
500 Hz, 343 m/s, source 20 m/s approaching.
- f_obs = 500×343/(343-20) = 531 Hz (higher)
✓ 531 Hz
Example 2
Ambulance Receding
500 Hz, source 20 m/s receding.
- f_obs = 500×343/(343+20) = 472 Hz (lower)
✓ 472 Hz
Example 3
Observer Moving
1000 Hz static, observer 30 m/s approaching.
- f_obs = 1000×(343+30)/343 = 1087 Hz
✓ 1087 Hz
Real-World Applications
Physics Students
Understand Doppler effect with real calculations.
Emergency Services
Understand frequency shifts from vehicle motion.
Astronomers
Apply to galactic redshift.
Acoustics
Calculate frequency shifts in acoustic systems.
Common Mistakes to Avoid
⚠️
Doppler shifts pitch not volume
It changes frequency (pitch), not amplitude (loudness).
⚠️
Temperature-dependent sound speed
343 m/s at 20°C. At 0°C: 331 m/s. Use the correct value.
Frequently Asked Questions
What is the Doppler effect? ▾
Frequency change when source and observer move relative to each other.
How do radar guns work? ▾
Emitted microwaves reflect off vehicles; Doppler shift reveals speed.
Cosmological redshift? ▾
Distant galaxies are redshifted because the universe is expanding — evidence for the Big Bang.