Doppler Effect Calculation

Formula:

For sound waves (subsonic speeds):

f' = f × (v ± vₒ) / (v ∓ vₛ)

Where:

  • f' = Observed frequency
  • f = Source frequency
  • v = Speed of sound in medium
  • vₒ = Observer speed (positive if moving toward source)
  • vₛ = Source speed (positive if moving toward observer)

Results

Observed Frequency (f'):

--

Hz

Frequency Shift (Δf):

--

Hz

About the Doppler Effect

The Doppler Effect is the change in frequency or wavelength of a wave in relation to an observer who is moving relative to the wave source. It's named after Austrian physicist Christian Doppler, who proposed it in 1842.

  • Medical Ultrasound: Measure blood flow velocity
  • Radar: Determine speed of vehicles or weather patterns
  • Astronomy: Measure radial velocity of stars and galaxies (redshift/blueshift)
  • Aviation: Measure aircraft speed
  • Meteorology: Track storms and precipitation

For sound waves: The speed of sound in air varies with temperature. At 20°C (68°F), it's approximately 343 m/s (1,235 km/h; 767 mph).

For light waves: The relativistic formula must be used when relative speeds approach a significant fraction of the speed of light (3×10⁸ m/s).

In both cases, motion toward the source/observer increases the observed frequency (blueshift), while motion away decreases it (redshift).