Klitzing, Klaus von

▪ German physicist

born June 28, 1943, Schroda [Sroda], German-occupied Poland

      German physicist who was awarded the Nobel Prize for Physics in 1985 for his discovery that under appropriate conditions the resistance offered by an electrical conductor is quantized; that is, it varies by discrete steps rather than smoothly and continuously.

      At the end of World War II, Klitzing was taken by his parents to live in West Germany. He attended the Technical University of Brunswick, graduating in 1969, and then earned a doctorate in physics at the University of Würzburg in 1972. In 1980 he became a professor at the Technical University of Munich, and in 1985 he became director of the Max Planck Institute for Solid State Physics in Stuttgart, Ger.

      Klitzing demonstrated that electrical resistance occurs in very precise units by using the Hall effect. The Hall effect denotes the voltage that develops between the edges of a thin current-carrying ribbon placed between the poles of a strong magnet. The ratio of this voltage to the current is called the Hall resistance. When the magnetic field is very strong and the temperature very low, the Hall resistance varies only in the discrete jumps first observed by Klitzing. The size of those jumps is directly related to the so-called fine-structure constant, which defines the mathematical ratio between the motion of an electron in the innermost orbit around an atomic nucleus to the speed of light.

      The significance of Klitzing's discovery, made in 1980, was immediately recognized. His experiments enabled other scientists to study the conducting properties of electronic components with extraordinary precision. His work also aided in determining the precise value of the fine-structure constant and in establishing convenient standards for the measurement of electrical resistance.

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