Christian Johann Doppler, born November 29, 1803 in Salzburg, Austria died Christian Doppler an Austrian Physicist who first describedhow the detected frequency of light and sound waves is affected by the relative motion ofthe source and the detector. This aspect became known as the Doppler Effect. Christianwas educated at the Polytechnical Institute in Vienna. Doppler became director of thephysical Institute and professor of experimental physics of the University of Vienna in1850. In 1842 he published Uber das farbige Licht der Dopperlsterne which meansConcerning the Coloured Light of Double Stars, which contained his first statement ofthe Doppler effect. He then theorized that since the pitch of sound from a moving sourcevaries for a stationary observer, the colour of the light from a star should alter, accordingto the star's velocity relative to Earth.The cause of the Doppler effect isn't just sound. There is also light. As thesource of the wave approaches or moves away to a person. For example you can tell if alight is far away, or close to you without really judging where the light is at. All you haveto do is if a light is far away from you then the light is small, and continues to get smalleras it moves away. And if the light is moving towards you then the light becomes bigger,and brighter. Another example of this is if you ever drove in a car at night you can see acar from far away but the headlights of the other car look like they are more seperatedapart. And as the vehicle moves closer to you, the lights seem that they are getting closertogether.What happens to a pitch or frequency when the source is moving towards theperson or away from him/her? It has been established from sound waves that thefrequency is higher when a sound source is moving toward the person and lower when itis moving away from him/her. Another example of the Doppler effect is the way a policecar’s siren changes in pitch when it passe...
