A D V E N T U R E S in C Y B E R S O U N DAntoine César, Alexandre Edmond and Antoine Henri Becquerel
Antoine César Becquerel : 1788 - 1878 A French Physicist, Antoine César Becquerel was the first to use electrolysis as a means of isolating metals from their ores. In 1837 he was awarded the Copley Medal of the Royal Society and became Professor at the Musée de' Histoire Naturelle. In 1839 he researched the electrochemical effects of light.
Alexandre Edmond Becquerel : 1820 - 1891 French Physicist, son and assistant of Antoine César. Alexandre Edmond Becquerel succeeded his father as Professor at the Musée de' Histoire Naturelle in 1878. He researched solar radiation, diamagnetism and constructed the phosphoroscope.
Antoine Henri Becquerel : 1852 - 1908 The French physicist Antoine Henri Becquerel, (b. Dec. 15, 1852, d. Aug. 25, 1908), and grandson of Antoine César is known for his discovery of radioactivity (1896) for which he shared the 1903 Nobel Prize for physics with Marie and Pierre Curie. Among a variety of luminescent crystals, Becquerel found that only those containing uranium emitted radiation naturally. This significant discovery opened the way to nuclear physics. He subsequently discovered that the radiations of radium comprise electrons, and he was the first to supply experimental evidence of the phenomenon of radioactive transformation. He was elected to the Academy of Sciences (1889) and appointed professor of physics at the Museum of Natural History (1892) and the Ecole Polytechnique (1895). E. Robert Paul
Antoine Henri Becquerel was born into a family of scientists. His grandfather, Antoine César, had made important contributions in the field of electrochemistry while his father, Alexandre Edmond, had investigated the phenomena of fluorescence and phosphorescence. Becquerel not only inherited their interest in science, he also inherited the minerals and compounds studied by his father. And so, upon learning how Wilhelm Röntgen discovered X rays by observing the fluorescence they produced, Becquerel had a ready source of fluorescent materials with which to pursue his own investigations of these mysterious rays. The material Becquerel chose to work with was a double sulfate of uranium and potassium which he exposed to sunlight and placed on photographic plates wrapped in black paper. When developed, the plates revealed an image of the uranium crystals. Becquerel concluded "that the phosphorescent substance in question emits radiation which penetrates paper opaque to light." Initially he believed that the sun's energy was being absorbed by the uranium which then emitted X rays. Further investigation, on the 26th and 27 of February, was delayed because the skies over Paris were overcast and the uranium-covered plates Becquerel intended to expose to the sun were returned to a drawer. On the first of March, he developed the photographic plates expecting only faint images to appear. To his surprise, the images were clear and strong. This meant that the uranium emitted radiation without an external source of energy such as the sun. Becquerel had discovered radioactivity, the spontaneous emission of radiation by a material. Later, Becquerel demonstrated that the radiation emitted by uranium shared certain characteristics with X rays but, unlike X rays, could be deflected by a magnetic field and therefore must consist of charged particles. For his discovery of radioactivity, Becquerel was awarded the 1903 Nobel Prize for physics.
Antoine Henri Becquerel was a physicist and become a professor of physics 1892 at the Musém d´Histoire naturelle in Paris, a position that was held before him by his father Alexandre Edmond as well as by his grandfather Antoine César Antoine Henri Becquerel was in fact triple-professor in Paris, since he also became professor at the École Polytechnique and the Conservatoire National des Arts et Métiers. He studied the physical nature of the phosphorescenct phenomena, and published a report 1885 on the connection between absorption of light and phosphorescence in his experiments with uranium. Becquerel was awarded the third Nobel Prize in Physis 1903 for "the discovery of spontaneous radioactivity", together with Marie and Pierre Curie for "work on the radiation phenomena discovered by Becquerel". Henri Becquerel´s Nobel address in Stockholm, December 11 1903, was entitled "On a new property of matter, radioactivity". Like Röntgen's discovery of x-rays in 1895, the discovery of radioactivity in Paris on Sunday 1 March 1896 by Becquerel was favoured by chance, when he tested the hypothesis that the penetrating x-rays might be related to the rays involved in phosphorescence. Inspired by Röntgen's discovery, Becquerel became interested in a study of the possible emission of x-rays from uranium compounds when exposed to sunlight. Several days of overcast weather in February 1896 delayed his experiments. For some reason, which is not known, he developed the photographic plates which he had been kept in darkness in his desk drawer and upon which the uranium had been placed a few days earlier. To his astonishment the photographic plate showed a sharp black region just beneath the uranium compound. During the spring Becqurel investigated various properties of the unknown radiation from the uranium, i.e. absorption properties, discharging an electroscope and similarities and differences with Röntgen's x-rays. In November 1896 he could show that the uranium kept in darkness for half a year induced the same blackening of photographic plates as they did earlier that year. Becquerel left off working with the radiation phenomena but started again two years later, partly in collaboration with the Curies. In 1900 the French Academy of Sciences proposed that Henri Becquerel should be awarded the newly established Nobel prize. The proposal was repeated later with the addition that the Nobel prize should be shared between Becquerel and Marie & Pierre Curie. The name of the phenomena 'radioactivity' was suggested by Marie Curie.
Antoine Henri Becquerel was from a family of eminent scientists, both his father and grandfather were prominent French physicists. In 1892 he became professor of applied physics at the Musee d'Histoire Naturelle (Museum of Natural History) in Paris, a position that both his father and grandfather had held before him. In 1895 he received an appointment at L'Ecole Polytechnique in Paris. His discovery of radioactivity resulted from that combination of things that often appears to be associated with great discoveries, the discovery comes from research whose goal is to understand something else. After the discovery of x-rays by Röntgen in 1895, Becquerel began an investigation of their properties. This was done by using a Crooke's Tube (an evacuated tube in which one could produce a high voltage discharge to produce the electrons when the electrons were rapidly decelerated upon colliding with a copper anode). To view the x-rays one used various phophorescent salts. He noted that the uranyl salts he was using for these fluorescence studies appeared to give off their own radiation. This radiation was determined to be different from that of the x-rays he had been studying and was, in fact, shown to be three different kinds of radiation which were called alpha, beta and gamma rays. We now understand that the first two of these are not "rays", but are in fact particles, and that only the last is a form of electromagnetic radiation. If Becquerel had not been investigating x-rays, he probably would not have discovered radioactivity. If he had not been trained to be inquisitive, that is if he had convinced himself that there was probably something wrong with his experiment or if he had not recognized what was unusual, he probably would not have discovered radioactivity. Lastly, if he had not pursued an answer to what he saw, if he had just returned to doing what he had been doing, he probably would not have discovered radioactivity. All three of these things appear to be necessary, though by no means sufficient, to the successful scientist
1. an inquisitive nature Source: http://144.26.13.41/phyhist/becquere.htm
On February 24, 1896, Antoine Henri Becquerel reported before the Académie des Sciences in Paris that a specific uranium-bearing crystal which had been brought to shine under the action of sunlight and had then been placed on a photographic plate wrapped in dark paper had blackened the photoplate. As early as one week later he recognized that the crystal produced the same blackening effect even when it was in the dark and did not shine at all. Even when thin glass plates or tin foils were placed between crystal and photoplate, this phenomenon did not disappear. The crystal obviously emitted a penetrating radiation similar to the X-radiation which had been discovered shortly before. With this, a new natural phenomenon had been discovered, which two years later was referred to by Marie Curie as "radioactivité". For the moment, radioactivity was observed only in uranium-containing substances. The professional circles at home and abroad were informed about Becquerel's discovery, but they were not much interested in it, the less so as the radiation was weak and a great number of experts did not quite believe it. The scientists had thrown themselves into the investigation into X-radiation, for the world was fascinated by the perspectives which the application of this far more intense radiation opened up in the field of medicine. So there was not much time left for the study of radioactivity. Only when the Curies appeared on the scene in 1898 and discovered the highly radioactive radium was life put into this area of research. The development that followed ultimately led to a new concept of physics. Radioactivity was the basis for the theories advanced in the 20th century about the structure of matter and the structure of the atoms. The credit for having laid the foundation of this goes to Becquerel. In Germany, in the first years after radioactivity had been discovered, it was chiefly Julius Elster and Hans Geitel, teachers at the Wolfenbettel Grammar School, and Fritz Giesel from Braunschweig, who devoted themselves to the study of the properties of the "Becquerel rays" and whose publications won international recognition.
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