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Joseph John Thomson est un physicien britannique qui a découvert l'électron et les isotopes. Il a reçu le prix Nobel de physique en 1906 et a développé le modèle de l'atome de plum pudding.
- Overview
- Education and early career
- Discovery of the electron
- Legacy
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J.J. Thomson (born December 18, 1856, Cheetham Hill, near Manchester, England—died August 30, 1940, Cambridge, Cambridgeshire) English physicist who helped revolutionize the knowledge of atomic structure by his discovery of the electron (1897). He received the Nobel Prize for Physics in 1906 and was knighted in 1908.
Thomson was the son of a bookseller in a suburb of Manchester. When he was only 14, he entered Owens College, now the University of Manchester. He was fortunate in that, in contrast with most colleges at the time, Owens provided some courses in experimental physics. In 1876 he obtained a scholarship at Trinity College, Cambridge, where he remained for the rest of his life. After taking his B.A. degree in mathematics in 1880, the opportunity of doing experimental research drew him to the Cavendish Laboratory. He began also to develop the theory of electromagnetism. As set forth by James Clerk Maxwell, electricity and magnetism were interrelated; quantitative changes in one produced corresponding changes in the other.
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Prompt recognition of Thomson’s achievement by the scientific community came in 1884 with his election as a fellow of the Royal Society of London and appointment to the chair of physics at the Cavendish Laboratory. Thomson entered physics at a critical point in its history. Following the great discoveries of the 19th century in electricity, magnetism, and thermodynamics, many physicists in the 1880s were saying that their science was coming to an end like an exhausted mine. By 1900, however, only elderly conservatives held this view, and by 1914 a new physics was in existence, which raised, indeed, more questions than it could answer. The new physics was wildly exciting to those who, lucky enough to be engaged in it, saw its boundless possibilities. Probably not more than a half dozen great physicists were associated with this change. Although not everyone would have listed the same names, the majority of those qualified to judge would have included Thomson.
Thomson’s most important line of work, interrupted only for lectures at Princeton University in 1896, was that which led him in 1897 to the conclusion that all matter, whatever its source, contains particles of the same kind that are much less massive than the atoms of which they form a part. They are now called electrons, although he originally called them corpuscles. His discovery was the result of an attempt to solve a long-standing controversy regarding the nature of cathode rays, which occur when an electric current is driven through a vessel from which most of the air or other gas has been pumped out. Nearly all German physicists of the time held that these visible rays were produced by occurrence in the ether—a weightless substance then thought to pervade all space—but that they were neither ordinary light nor the recently discovered X-rays. British and French physicists, on the other hand, believed that these rays were electrified particles. By applying an improved vacuum technique, Thomson was able to put forward a convincing argument that these rays were composed of particles. Furthermore, these rays seemed to be composed of the same particles, or corpuscles, regardless of what kind of gas carried the electric discharge or what kinds of metals were used as conductors. Thomson’s conclusion that the corpuscles were present in all kinds of matter was strengthened during the next three years when he found that corpuscles with the same properties could be produced in other ways—e.g., from hot metals. Thomson may be described as “the man who split the atom” for the first time, although “chipped” might be a better word, in view of the size and number of electrons. Although some atoms contain many electrons, the electrons’ total mass is never so much as 1/1,000 that of the atom.
By the turn of the century, most of the scientific world had fully accepted Thomson’s far-reaching discovery. In 1903 he had the opportunity to amplify his views on the behaviour of subatomic particles in natural phenomena when, in his Silliman Lectures at Yale University, he suggested a discontinuous theory of light; his hypothesis foreshadowed Albert Einstein’s later theory of photons. In 1906 he received the Nobel Prize for Physics for his researches into the electrical conductivity of gases; in 1908 he was knighted; in 1909 he was made president of the British Association for the Advancement of Science; and in 1912 he received the Order of Merit.
Thomson was, however, by no means a scientific recluse. During his most fruitful years as a scientist, he was administrative head of the highly successful Cavendish Laboratory. (It was there that he met Rose Elizabeth Paget, whom he married in 1890.) He not only administered the research projects but also financed two additions to the laboratory buildings primarily from students’ fees, with little support from the university and colleges. Except for its share of a small government grant to the Royal Society to aid all British universities and all branches of science, the Cavendish Laboratory received no other government subsidy, nor were there contributions from charitable corporations or industry. A gift from a devoted staff member made possible the purchase of a small liquid-air machine essential for Thomson’s research on positive rays, which greatly increased knowledge of the recently discovered atomic nuclei.
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Thomson was, moreover, an outstanding teacher; his importance in physics depended almost as much on the work he inspired in others as on that which he did himself. The group of men he gathered around him between 1895 and 1914 came from all over the world, and after working under him many accepted professorships abroad. Seven Nobel Prizes were awarded to those who worked under him. It was while working with Thomson at the Cavendish Laboratory in 1910, for example, that Ernest Rutherford performed the research that led to the modern understanding of the internal structure of the atom. In the process, the Rutherford atomic model supplanted the so-called plum-pudding model of atomic structure proposed by Lord Kelvin; the latter is known as the Thomson atomic model because of the strong support Thomson gave it for a few years.
To a large extent, it was Thomson who made atomic physics a modern science. The studies of nuclear organization that continue even to this day and the further identification of elementary particles all followed his most outstanding accomplishment, his discovery of the electron in 1897. Although this physics has raised many theoretical questions, fr...
Learn about J.J. Thomson, the English physicist who discovered the electron and won the Nobel Prize for Physics in 1906. Explore his life, education, career, and contributions to the Cavendish Laboratory and the science of electromagnetism.
- George Paget Thomson
2 févr. 2020 · Découvrez la vie et l'œuvre de Sir Joseph John Thomson, le physicien anglais qui a révolutionné la science en découvrant l'électron et en proposant un modèle de l'atome. Apprenez ses contributions à la physique, la chimie et l'enseignement, ainsi que ses distinctions et ses anecdotes.
Joseph John Thomson (1856-1940) est un physicien britannique, prix Nobel de physique en 1906 pour sa découverte de l'électron. Il a aussi contribué à la spectroscopie, à la séparation des isotopes et à la physique des rayons cathodiques.
30 mai 2021 · En 1904, Joseph John Thomson proposa une évolution du modèle atomique de Dalton, donnant naissance au célèbre modèle de Thomson, une théorie révolutionnaire qui tentait d'expliquer deux propriétés fondamentales des atomes de l'époque.
- 3 min
7 mars 2024 · Découvrez la vie et l'œuvre de JJ Thomson, le physicien britannique qui a identifié l'électron et proposé le modèle atomique de Thomson. Apprenez comment il a contribué à la physique quantique, à l'éducation et à la recherche scientifique.
Physicien britannique, prix Nobel de physique 1906, qui établit les fondements de la théorie électronique et mesure la charge et la masse de l'électron. Découvre aussi le spectrographe de masse et le modèle atomique à noyau positif.
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