Heinrich Georg Barkhausen
Heinrich Georg Barkhausen (December 2, 1881 - February 20, 1956), born at Bremen was a German physicist.
Born into a patrician family in Bremen, he showed interest in natural sciences from an early age. He studied at the Technical University of Munich (1901), TU Berlin (1902) and University of Munich (1903) and Berlin before obtaining a doctorate at the University of Göttingen in 1907.
He became Professor for Electrical Engineering at the Technische Hochschule Dresden in 1911 at the age of 29, thus obtaining the world's first chair in this discipline.
He discovered in 1919 an effect named after him, the Barkhausen effect, which suggested that ferromagnetic materials contain regions of like-oriented atoms. Induced changes in the magnetic orientation of these domains affect the whole domain and not individual atoms. With suitable equipment, these changes of orientation (jumps) can be heard.
The oft-quoted but incorrect Barkhausen Stability Criterion claims that an oscillator will oscillate when the total phase shift from input to output back to input is 360 degrees and the system gain is at least 1.
Four volume teaching text: "Lehrbuch der Elektronenröhren, Elektronenröhren und ihre technischen Anwendungen."
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