The Doppler effect It is a phenomenon in which an apparent change occurs in the frequency of sound, or in the wavelength of light, which is due to the relative movement of the entity that emits it in relation to an observer who is fixed.
If a sound source approaches a fixed observer it will emit a higher sound than when it moves away from him, which commonly occurs when hearing the characteristic sound of a moving ambulance. In the case of light, when a light source approaches it takes on a bluish hue while when it moves away it tends to a red color, this is not always visible to the naked eye, making it necessary to use instruments to be able to highlight it.
The Doppler effect has a large number of uses in different fields, in the case of sound it is very useful in the detection of objects that are outside the visual field as occurs with radar and in satellite location by GPS. It is also used to locate submerged objects in seas and oceans, or to determine the course and speed of military targets.
In the case of light, astrophysicists have been able to use this effect to determine the movements of stars and galaxies, it has also highlighted the fact that the universe is in a process of expansion and not of approach.
One of the areas of knowledge in which it has had the greatest application is in medicine, specifically in diagnostic imaging through ultrasound studies in the cardiovascular system, in this sense, cardiac ultrasound or echocardiography allows visualizing the dimensions of the various cavities of the heart and the vessels that arrive and depart from it, as well as the pressure inside them, which allows a large number of diagnoses to be made without the need for invasive procedures.
In addition, the speed and direction of blood flow can be identified, which makes it possible to reveal abnormal conditions such as flow obstructions compatible with stenosis, or its abnormal retrograde flow known as regurgitation in states of insufficiency of the different valves. This is better visualized with the Doppler effect added to the ultrasound that shows the blood flows that approach the observer in blue and those that move away in red, thus being able to identify the direction of said flow. It is also used in the evaluation of the blood vessels of the extremities, both in the arterial and venous systems.
