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Wilhelm Röntgen

discoverer of x-rays

Wilhelm Konrad Rontgen

Wilhelm Konrad Röntgen was born in Lennep, Germany, on March 27, 1845, the only child of a cloth merchant. His family moved to Apeldoorn, Netherlands, when he was three. He received his early education at the Institute of Martinus Herman van Doorn, a boarding school in Apeldoorn, where he showed no special aptitude for any subject but did display a love of nature and a knack for making mechanical contrivances.

In 1862 Röntgen entered a technical school in Utrecht, but he was expelled before he could graduate after being accused of drawing a caricature of a teacher (whether he or someone else actually committed the act is not clear). In 1865, after being rejected by the University of Utrecht because he had failed to complete his secondary education, he entered the Federal Polytechnic Institute in Zürich, where he studied mechanical engineering. He then came under the tutelage of August Kundt, a professor of physics at the University of Zürich, who recognized Röntgen's talent and gave him a job in his laboratory, enabling him to begin a career in physics teaching. He received his Ph.D. from the University of Zürich in 1869, after which he followed Kundt to the University of Würzburg, and then, in 1873, to the University of Strasbourg, where he became a lecturer in 1874. He subsequently became a professor at the Academy of Agriculture at Hohenheim, Württemberg (1875), professor of physics at the University of Strasbourg (1876), chair of physics at the University of Giessen (1879), chair of physics at the University of Würzburg (1888), and chair of physics at the University of Munich (1900).

In 1872, Röntgen married Anna Bertha Ludwig, in Apeldoorn. The couple had no children of their own, but in 1887 they adopted Josephine Bertha Ludwig, then aged 6, the daughter of Mrs. Röntgen's only brother. Anna died of intestinal cancer in 1919, four years before her husband, who died in Munich on February 10, 1923.

His Work

Röntgen's first work, dealing with the specific heats of gases, was published in 1870, followed a few years later by a paper on the thermal conductivity of crystals. Among other problems he studied were the electrical and other characteristics of quartz, the influence of pressure on the refractive indices of various fluids, the modification of the planes of polarised light by electromagnetic influences, the variations in the functions of the temperature and the compressibility of water and other fluids, and the phenomena accompanying the spreading of oil drops on water.

Röntgen was working with cathode ray tubes when he made the discovery that made him famous. On the evening of November 8, 1895, he found that, if the discharge tube is enclosed in a sealed, thick black carton to exclude all light, and if he worked in a dark room, a paper plate covered on one side with barium platinocyanide placed in the path of the rays became fluorescent even when it was as far as two meters from the discharge tube. During subsequent experiments he found that objects of different thicknesses interposed in the path of the rays showed variable transparency to them when recorded on a photographic plate. When he held the hand of his wife in the path of the rays over a photographic plate, he observed after development of the plate an image of his wife's hand which showed the shadows thrown by the bones of her hand and that of a ring she was wearing, surrounded by the penumbra of the flesh, which was more permeable to the rays and therefore threw a fainter shadow. In further experiments, Röntgen showed that the new rays are produced by the impact of cathode rays on a material object. Because their nature was then unknown, he gave them the name X-rays.

Röntgen was rewarded for his discovery with the Rumford medal of the Royal Society in 1896, and with the first ever Nobel Prize in Physics in 1901.


Nobel Foundation
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See Also

Nobel Prize in Physics

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This page was last updated on 09/03/2018.