If the observer and source are moving toward each other, then the frequency increases and the wavelength decreases.
What is dopper effect?
The Doppler effect defines the shift in frequency of a wave sound caused by movement of the wave source and/or receiver. We'll talk about it in terms of sound waves, but the Doppler effect applies to any type of wave.
The Doppler effect, like ultrasound, has a wide range of uses, from medical (with sound) to police radar and astronomy (with electromagnetic waves).
The Doppler effect happens when there is relative motion between the observer and the source, not just for sound.
Doppler shifts, for example, occur in the frequency of sound, light, and water waves. When ultrasonography is reflected from blood in a medical diagnosis, Doppler shifts can be utilized to assess velocity.
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