Christian Doppler

Picture of Christian Doppler Image courtesy of the University of St. Andrews, Scotland Christian Doppler was an Austrian mathematician who lived between 1803-1853. He is known for a principle he proposed in 1842. This is now known as the Doppler Effect. He thought that the pitch of a sound would be different if the source of the sound was moving. Doppler's hypothesis was tested by Buys Ballot in 1845. He used two sets of trumpeters. One set was at a train station and one set was on an open train car. The train car was pulled past the station. Both groups of trumpeters played the same note but the notes didn't match. The frequency of the notes had changed. Later, a scientist named Fizeau went further with Doppler's work and applied it to light, too. Doppler had only worked out his theory for sound.

How could Doppler tell the frequency of the notes had changed?

Last modified January 22, 2009 by Julia Genyuk.
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