What is meant by Doppler Effect?


#1

The frequency of the reflected ultrasonic energy is increased or decreased by a moving interface. The amount of frequency shift can be expressed as, f=2V/λ,

f=shift in frequency of the reflected wave, V=velocity of the interface, λ=wavelength of the transmitted ultrasound.

The frequency increases when interface moves towards the transducer & decreases when it moves away.