O Doppler effect was proposed in 1842 by the Austrian physicist Johann Christian Doppler (1803 – 1853) and consists of the alteration of the frequency of a sound source perceived by an observer. This change in the observed frequency value occurs because of the existence of relative motion between the wave source and the observer. The experimental study of the Doppler effect was only carried out in 1845, by Buys Ballot (1817 – 1890), using a locomotive that pulled a wagon where there were trumpet players.
The Doppler effect is not a characteristic phenomenon only of sound waves, but it can also occur with electromagnetic waves, like the microwave, radio waves, infra-red and visible light. Through the Doppler effect of light, Edwin Hubble (1889 – 1953) was able to prove the universe expansion, showing the redshift of light emitted by galaxies.
Doppler Effect in Medicine
The Doppler effect is used in imaging diagnoses in exams that provide the mapping of the blood flow, enabling the determination of the direction and speed of the blood in the heart chambers, for example.
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By placing a source of inaudible sound waves, that is, they have a frequency outside the audible sound spectrum, the device picks up the waves that were reflected (echo) by Red Cells, enabling the determination of blood flow characteristics. The images produced by this type of exam are obtained without the need to submit the patient to sources of radiation and can be used for the prevention and monitoring of various diseases.
Imaging diagnostics through the Doppler effect can be applied to pregnant women for the verification of conditions of irrigation and oxygenation of fetal organs.
Doppler echocardiogram
Using the principles of the Doppler effect, the Doppler Echocardiogram is an exam that provides information about the conditions of the heart. Through this examination, it can be determined:
- Size of heart chambers;
- Conditions of muscles that make up the heart;
- Operation of valves;
- Possible malformation;
- Blood flow.
By Joab Silas
Graduated in Physics
Would you like to reference this text in a school or academic work? Look:
JUNIOR, Joab Silas da Silva. "Doppler effect diagnostics"; Brazil School. Available in: https://brasilescola.uol.com.br/fisica/diagnosticos-por-efeito-doppler.htm. Accessed on June 27, 2021.
