How the doppler effect is used in medicine?
It is used in doppler ultrasound to measure the velocity of blood in a patient's arteries.
In a Doppler ultrasound scan pulses of ultrasound waves are directed along arteries so that they will reflect off of blood cells. The blood cells are in motion so the reflected waves will have their wavelength shortened (or lengthened) according to the Doppler equation.
v is the speed of the blood.
c is the speed of the ultrasound in the medium.
Δλ is the change in wavelength.
λ is the transmitted wavelength.
It is then possible to calculate the velocity of the blood.