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J. J. Thomson

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Born
Joseph John Thomson

(1856-12-18)18 December 1856
Died30 August 1940(1940-08-30) (aged 83)
Cambridge, England
NationalityEnglish
CitizenshipBritish
Alma materOwens College (now the University of Manchester)
Trinity College, Cambridge (BA)
Known forPlum pudding model
Discovery of electron
Discovery of isotopes
Mass spectrometer invention
First m/e measurement
Proposed first waveguide
Thomson scattering
Thomson problem
Coining term 'delta ray'
Coining term 'epsilon radiation'
Thomson (unit)
ChildrenGeorge Paget Thomson, Joan Paget Thomson
AwardsSmith's Prize (1880)
Royal Medal (1894)
Hughes Medal (1902)
Nobel Prize in Physics (1906)
Elliott Cresson Medal (1910)
Copley Medal (1914)
Albert Medal (1915)
Franklin Medal (1922)
Faraday Medal (1925)
Dalton Medal (1931)
Scientific career
FieldsPhysics
InstitutionsTrinity College, Cambridge
Academic advisorsJohn Strutt (Rayleigh)
Edward John Routh
Notable studentsCharles Glover Barkla
Charles T. R. Wilson
Ernest Rutherford
Francis William Aston
John Townsend
J. Robert Oppenheimer
Owen Richardson
William Henry Bragg
H. Stanley Allen
John Zeleny
Daniel Frost Comstock
Max Born
T. H. Laby
Paul Langevin
Balthasar van der Pol
Geoffrey Ingram Taylor
Niels Bohr
George Paget Thomson
Debendra Mohan Bose
Lawrence Bragg
Signature
Jjthomson sig.svg
External video
Title page On the Chemical Combination of Gases by Joseph John Thomson 1856-1940.jpgOM PRS[1] (18 December 1856 – 30 August 1940) was a British physicist and Nobel Laureate in Physics, credited with the discovery of the electron, the first subatomic particle to be discovered.

In 1897, Thomson showed that cathode rays were composed of previously unknown negatively charged particles (now called electrons), which he calculated must have bodies much smaller than atoms and a very large charge-to-mass ratio.[2] Thomson is also credited with finding the first evidence for isotopes of a stable (non-radioactive) element in 1913, as part of his exploration into the composition of canal rays (positive ions). His experiments to determine the nature of positively charged particles, with Francis William Aston, were the first use of mass spectrometry and led to the development of the mass spectrograph.[2][3]

Thomson was awarded the 1906 Nobel Prize in Physics for his work on the conduction of electricity in gases.[4]

Education and personal life

Joseph John Thomson was born on 18 December 1856 in Cheetham Hill, Manchester, Lancashire, England. His mother, Emma Swindells, came from a local textile family. His father, Joseph James Thomson, ran an antiquarian bookshop founded by Thomson’s great-grandfather. He had a brother, Frederick Vernon Thomson, who was two years younger than he was.[5] J. J. Thomson was a reserved yet devout Anglican.[6][7][8]

His early education was in small private schools where he demonstrated outstanding talent and interest in science. In 1870, he was admitted to Owens College in Manchester (now University of Manchester) at the unusually young age of 14. His parents planned to enroll him as an apprentice engineer to Sharp-Stewart & Co, a locomotive manufacturer, but these plans were cut short when his father died in 1873.[5]

He moved on to Trinity College, Cambridge, in 1876. In 1880, he obtained his Bachelor of Arts degree in mathematics (Second Wrangler in the Tripos[9] and 2nd Smith's Prize).[10] He applied for and became a Fellow of Trinity College in 1881.[11] Thomson received his Master of Arts degree (with Adams Prize) in 1883.[10]

Family

In 1890, Thomson married Rose Elisabeth Paget. Beginning in 1882, women could attend demonstrations and lectures at the University of Cambridge. Rose Paget, daughter of Sir George Edward Paget, a physician and then Regius Professor of Physic at Cambridge at the church of St. Mary the Less, was interested in physics. She attended demonstrations and lectures, among them Thomson's. Their relationship developed from there.[12] They had two children: George Paget Thomson, who was also awarded a Nobel Prize for his work on the wave properties of the electron, and Joan Paget Thomson (later Charnock),[13] who became an author, writing children's books, non-fiction and biographies.[14]

Career and researchIn 1897, Thomson showed that cathode rays were composed of previously unknown negatively charged particles (now called electrons), which he calculated must have bodies much smaller than atoms and a very large charge-to-mass ratio.[2] Thomson is also credited with finding the first evidence for isotopes of a stable (non-radioactive) element in 1913, as part of his exploration into the composition of canal rays (positive ions). His experiments to determine the nature of positively charged particles, with Francis William Aston, were the first use of mass spectrometry and led to the development of the mass spectrograph.[2][3]

Thomson was awarded the 1906 Nobel Prize in Physics for his work on the conduction of electricity in gases.[4]

Joseph John Thomson was born on 18 December 1856 in Cheetham Hill, Manchester, Lancashire, England. His mother, Emma Swindells, came from a local textile family. His father, Joseph James Thomson, ran an antiquarian bookshop founded by Thomson’s great-grandfather. He had a brother, Frederick Vernon Thomson, who was two years younger than he was.[5] J. J. Thomson was a reserved yet devout Anglican.[6][7][8]

His early education was in small private schools where he demonstrated outstanding talent and interest in science. In 1870, he was admitted to Owens College in Manchester (now University of Manchester) at the unusually young age of 14. His parents planned to enroll him as an apprentice engineer to Sharp-Stewart & Co, a locomotive manufacturer, but these plans were cut short when his father died in 1873.[5]

He moved on to Trinity College, Cambridge, in 1876. In 1880, he obtained his Bachelor of Arts degree in mathematics (Second Wrangler in the Tripos[9] and 2nd Smith's Prize).[10] He applied for and became a Fellow of Trinity College in 1881.[11] Thomson received his Master of Arts degree (with Adams Prize) in 1883.[10]

Family

In 1890, Thomson married Rose Elisabeth Paget. Beginning in 1882, women could attend demonstrations and lectures at the University of Cambridge. Rose Paget, daughter of Sir George Edward Paget, a physician and then Regius Professor of Physic at Cambridge at the church of St. Mary the Less, was interested in physics. She attended demonstrations and lectures, among them Thomson's. Their relationship developed from there.[12] They had two children: George Paget Thomson, who was also awarded a Nobel Prize for his work on the wave properties of the electron, and Joan Paget Thomson (later Charnock),[13] who became an author, writing children's books, non-fiction and biographies.[14]

Career and research<

J. J. Thomson's separation of neon isotopes by their mass was the first example of mass spectrometry, which was subsequently improved and developed into a general method by F. W. Aston and by A. J. Dempster.[2][3]

Earlier, physicists debated whether cathode rays were immaterial like light ("some process in the aether") or were "in fact wholly material, and ... mark the paths of particles of matter charged with negative electricity", quoting Thomson.[21] The aetherial hypothesis was vague,[21] but the particle hypothesis was definite enough for Thomson to test.

Magnetic deflection

Thomson first investigated

Thomson first investigated the magnetic deflection of cathode rays. Cathode rays were produced in the side tube on the left of the apparatus and passed through the anode into the main bell jar, where they were deflected by a magnet. Thomson detected their path by the fluorescence on a squared screen in the jar. He found that whatever the material of the anode and the gas in the jar, the deflection of the rays was the same, suggesting that the rays were of the same form whatever their origin.[27]

Electrical charge

While supporters of the aetherial theory accepted the possibility that negatively charged particles are produced in Crookes tubes,[citation needed] they believed that they are a mere by-product and that the cathode rays themselves are immaterial.[citation needed] Thomson set out to investigate whether or not he could actually separate the charge from the rays.

Thomson constructed a Crookes tube with an electrometer set to one side, out of the direct path of the cathode rays. Thomson could trace the path of the ray by observing the phosphorescent patch it created where it hit the surface of the tube. Thomson observed that the electrometer registered a charge only when he deflected the cathode ray to it with a magnet. He concluded that the negative charge and the rays were one and the same.[19]

Electrical deflection