Doppler Effect

1
Doppler Effect

• Distance and time

16.8
2
Moving Source or Detector

• Source successive wave fronts do not emanate
  from the same place
• Detector successive wave fronts are not detected
  at the same place
• Simulation http//www.astro.ubc.ca/scharein/a311
  /Sim/doppler/Doppler.html

3
Moving Source or Detector

• Equations of Motion
• Source xS vSt
• Detector xD D vDt
• nth wavefront xn vS(nT) v (t nT)

4
Differing Formulas

• Mine fD fS

• Difference Book uses v, source ahead of
  detector
• Moral Check your setup first

5
What does it mean?

• Check for various conditions

6
Doppler Shift of Light

• Relativistic Doppler shift

fD fS
where
b vS/c Detector frame of reference (vD 0)
7
Classical and Relativistic Shift

• Classical fD fS

8
Shock Waves

• Energy accumulates

16.9
9
Beyond Doppler Shift

• Sound waves travel from source with speed v

• What if source travels faster than v?

10
Sonic Boom

• Source NASA, Astronomy Picture of the Day
  (from U.S. Navy)

11
Supersonic Shock Wave
Source Young and Freedman, University Physics,
Fig. 16.35