Christian Johann Doppler was an Austrian physicist and mathematician. His family were stonemasons who had a successful business in Salzburg from 1674. He was born on November 29th, 1803. The family tradition would be for Christian to take over the family business, however, his health was never very good and her was quite frail so he could not follow in the family tradition. He started off by attending primary school in Salzburg and then secondary school in Linz. His parents questioned his academic potential until the professor of mathematics at the Salzburg Lyceum recommended that Doppler should study at Vienna Polytechnic Institute. Doppler began his studies there in 1822 and graduated by 1825. He then returned to Salzburg and attended philosophy lecutres at the Salzburg Lyceum. In 1829 he was appointed assistant in mathematics but this was only temperary and Doppler, rather older than most others, began to seek something permanent at the age of 30. During this time (1833) he applied to many schools and while this was going on he spent 18 months as a bookkeeper at a cottonspinning factory to earn his living. This was a sad and difficult time during Doppler's life so he ended up deciding to move to America. It wasn't until he received an offer of the post at the Technical Secondary School in Prague that things began to take a turn for the better.
He then married in 1836 and at this time he also began to teach higher mathematics for four hours a week at the Polytechnic, he continued doing this until 1838. He was then formally appointed to the post at the Polytechnic in March 1841. Doppler's students complained that his exams were too harsh and from this Doppler was investigated and reprimanded while students were permitted to retake the exam. Doppler felt as though he was innocent and demanded that the reprimand be withdrawn. His demand was a success by the end of 1844 but Doppler was not well enough to return to his duties until 1846. Prague was a difficuly time for him and he was then offered the professorship of mathematics, physics and mechanics at the Academy of Mines and Forests in Banska Stiavnica. He was then appointed to Vienna Polytechnic, and then once again on January 17, 1850 he was appointed as the first director of the new Institute of Physics at Vienna University. Christian Doppler had finally reached the high point of his career.
Although he wrote only one book (on arithmetic and algebra), he was the author of many important scientific papers, his first paper being being "A contribution to the theory of parallels". The most important of these was published in 1842, which explains what is now known as the Doppler effect; this had an immediate impact on acoustics and optics [The Encyclopedia Americana]. In 1845, an experiment was carried out near the Dutch town of Maarsen where musically trained observers were stationed along the tracks of Rhine Railroad and listened to trumpets being played in a passing railway car. By noting the pitch of the approaching and receding notes, the speed of the car was accurately estimated [http://imagine.gsfc.nasa/....]. By the 1850's it was widely used to explain several puzzling astronomical phenomena.
The Doppler effect dealt with apparent change in wavelength of sound or light caused by the motion of the source, observer or both. Waves emitted by a moving object as received by an observer will be compressed if approaching, elongated if receding. It occurs both in sound and light. Scientist, Fizeau, generalized Doppler's work and discovered that the Doppler effect also applied to light. How much the frequency changes depends on how fast the object is moving toward or away from the receiver [http://imagine....]. The frequency will be lower if the object is moving away from the observer and will be higher if moving towards. The "Doppler Shift" in frequency is due to the velocity and not the distance from the source. The formula used for the Doppler effect is:
F(app)=F(s) x [V(w) +or- V(s)]
Where: F(app) is the apparent frequency
F(s) is the frequency of source (original)
V(w) is the velocity of the wave
V(s) is the velocity of source/observer
With the +or-, the "+" is used when the observer and object are moving apart and the "-" is used when they are moving towards each other.
On the final date of March 17, 1853 Christian Johann Doppler passed away in Venice, Italy at the age of 50.
He then married in 1836 and at this time he also began to teach higher mathematics for four hours a week at the Polytechnic, he continued doing this until 1838. He was then formally appointed to the post at the Polytechnic in March 1841. Doppler's students complained that his exams were too harsh and from this Doppler was investigated and reprimanded while students were permitted to retake the exam. Doppler felt as though he was innocent and demanded that the reprimand be withdrawn. His demand was a success by the end of 1844 but Doppler was not well enough to return to his duties until 1846. Prague was a difficuly time for him and he was then offered the professorship of mathematics, physics and mechanics at the Academy of Mines and Forests in Banska Stiavnica. He was then appointed to Vienna Polytechnic, and then once again on January 17, 1850 he was appointed as the first director of the new Institute of Physics at Vienna University. Christian Doppler had finally reached the high point of his career.
Although he wrote only one book (on arithmetic and algebra), he was the author of many important scientific papers, his first paper being being "A contribution to the theory of parallels". The most important of these was published in 1842, which explains what is now known as the Doppler effect; this had an immediate impact on acoustics and optics [The Encyclopedia Americana]. In 1845, an experiment was carried out near the Dutch town of Maarsen where musically trained observers were stationed along the tracks of Rhine Railroad and listened to trumpets being played in a passing railway car. By noting the pitch of the approaching and receding notes, the speed of the car was accurately estimated [http://imagine.gsfc.nasa/....]. By the 1850's it was widely used to explain several puzzling astronomical phenomena.
The Doppler effect dealt with apparent change in wavelength of sound or light caused by the motion of the source, observer or both. Waves emitted by a moving object as received by an observer will be compressed if approaching, elongated if receding. It occurs both in sound and light. Scientist, Fizeau, generalized Doppler's work and discovered that the Doppler effect also applied to light. How much the frequency changes depends on how fast the object is moving toward or away from the receiver [http://imagine....]. The frequency will be lower if the object is moving away from the observer and will be higher if moving towards. The "Doppler Shift" in frequency is due to the velocity and not the distance from the source. The formula used for the Doppler effect is:
F(app)=F(s) x [V(w) +or- V(s)]
Where: F(app) is the apparent frequency
F(s) is the frequency of source (original)
V(w) is the velocity of the wave
V(s) is the velocity of source/observer
With the +or-, the "+" is used when the observer and object are moving apart and the "-" is used when they are moving towards each other.
On the final date of March 17, 1853 Christian Johann Doppler passed away in Venice, Italy at the age of 50.
0 comments:
Post a Comment