The Doppler effect applies to sound waves but not to electromagnetic waves.

Question

Quizplus · Accepted Answer

The Doppler effect applies to both sound waves and electromagnetic waves. It describes the shift in frequency as the source of the wave and the observer move relative to each other. For example, the pitch of an ambulance siren becomes higher as it approaches and lower as it moves away from an observer due to the Doppler effect, and the wavelength of light from a star may be shifted towards the red or blue end of the spectrum depending on whether the star is moving away from or towards Earth.

The Doppler Effect Applies to Sound Waves but Not to Electromagnetic