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Doppler,
Christian Johann Austrian physicist Born: Salzburg, November 29, 1803 Died: Venice, Italy, March 17, 1853 | |||||||||
Avogadro Becquerel Bohr Doppler Einstein Geiger Heisenberg Hertz Kirchhoff Planck Roentgen Rutherford Schrodinger |
Doppler planned to emigrate to America in 1835, because he despaired of receiving an academic appointment. At the last minute, he received word of an offer of a professorship in mathematics in Prague, and he abandoned his plans to emigrate. His name is forever associated with the Doppler effect, which is that a moving sound source appears to be more highly pitched to someone approaching the sound source, and more deeply pitched to someone moving away from the sound source. Doppler correctly explained the phenomenon by pointing out that sound waves, assisted by the motion of the source, reach the the ear at shorter intervals when the source is approaching - creating higher pitch. When the source recedes, the waves reach the ear at longer intervals, hence lower pitch. In 1842 he worked out a formula for relating pitch to the relative motion of the source and the observer. This was tested by placing trumpeters on the back of a train who played notes while the train moved backwards and forwards at various speeds. Doppler predicted that a similar effect would hold for light waves. This portion of the theory later turned out to be of great importance in the study of astronomy. | |||||||||
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