Understandings: The Doppler effect for light waves
Applications and skills: Sketching and interpreting the Doppler effect when there is relative motion between source and observer; Describing situations where the Doppler effect can be utilized; Solving problems involving the change in frequency or wavelength observed due to the Doppler effect to determine the velocity of the source/observer
Guidance: For electromagnetic waves, the approximate equation should be used for all calculations; Situations to be discussed should include the use of Doppler effect in radars and in medical physics, and its significance for the red-shift in the light spectra of receding galaxies
International-mindedness: Radar usage is affected by the Doppler effect and must be considered for applications using this technology
Utilization: Astronomy depends on the analysis of the Doppler Effect (for EM radiation) when dealing with fast moving objects
Data booklet:
What is the Doppler effect in EM radiation?
Answering questions about the Doppler effect in EM radiation
One of the postulates of special relativity (see that option for more information) is that the speed of light is the same for ALL observers. Thus there is no difference between a moving source and a moving observer. The term u in the equations for sound has no meaning either. The proportion of increase or decrease in the the frequency or wavelength of the observed radiation is given (approximately) by velocity of the object divided by the velocity of light (so for low velocities it is a very small change). Whether this is an increase or decrease depends on the direction of motion of the object / observer. If the distance between them is increasing then the wavelength will increase / frequency will decrease (known as red-shift). If the distance between them is decreasing then the wavelength will decrease / frequency will increase (known as blue-shift).
Oxford Physics 2014, 9. Wave Phenomena: pages 384 - 386
Hamper HL 2014, 5. Oscillations and waves: pages 98 - 200 (EM radiation)
Pages 91 - 98