J. J. Thomson

Sir
J. J. Thomson
OM FRS
Sir J. J. Thomson OM FRS
	Thomson in 1915
30th Master of Trinity College, Cambridge
	In office; 1918–1940
Preceded by	Henry Montagu Butler
Succeeded by	George Macaulay Trevelyan
42nd President of the Royal Society
	In office; 1915–1920
Preceded by	William Crookes
Succeeded by	Charles Sherrington
Personal details
Born	Joseph John Thomson; 18 December 1856; Manchester, England, UKGBI
Died	30 August 1940 (aged 83); Cambridge, England, UK
Resting place	Westminster Abbey, London
Alma mater	Owens College; Trinity College, Cambridge (BA, MA);
Known for	Postulating electromagnetic mass (1881); Discovering the electron (1897); Proposing the plum pudding model (1904); Discovering stable isotopes (1912);
Title	Cavendish Professor of Physics (1884–1919)
Spouse	Rose Paget (m. 1890)
Children	2, including George
Relatives	George Edward Paget ; (father-in-law)
Awards	See list Smith's Prize (1880) ; Adams Prize (1882) ; Royal Medal (1894) ; Hodgkins Medal (1902) ; Hughes Medal (1902) ; Nobel Prize in Physics (1906) ; Knight Bachelor (1908) ; Elliott Cresson Medal (1910) ; Order of Merit (1912) ; Copley Medal (1914) ; RSA Albert Medal (1915) ; Franklin Medal (1922) ; IET Faraday Medal (1925) ; Dalton Medal (1931) ;
	Scientific career
Fields	Atomic physics; Electromagnetism;
Institutions	Trinity College, Cambridge (1881–1940); Cavendish Laboratory ; (1884–1919);
Academic advisors	Lord Rayleigh; Balfour Stewart;
Notable students	See list Edward Appleton ; Francis Aston ; Charles Barkla ; Niels Bohr ; Max Born ; Debendra Mohan Bose ; Lawrence Bragg ; William Henry Bragg ; Hugh Longbourne Callendar ; Robert Ditchburn ; Thomas Laby ; Elizabeth Laird ; Paul Langevin ; Owen Richardson ; Ernest Rutherford ; Robert Strutt ; G. I. Taylor ; George Paget Thomson ; J. S. E. Townsend ; Balthasar van der Pol ; H. E. Watson ; C. T. R. Wilson ; Harold Albert Wilson ;
Signature

Sir Joseph John "J. J." Thomson (18 December 1856 – 30 August 1940) was a British physicist whose study of cathode rays led to his discovery of the electron, a subatomic particle with a negative electric charge.^[3]

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.^[4]

In 1906, Thomson was awarded the Nobel Prize in Physics "in recognition of the great merits of his theoretical and experimental investigations on the conduction of electricity by gases".^[5]

Thomson is credited with finding the first evidence for isotopes of a stable (non-radioactive) element in 1912, 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.^[4]^[6]

Thomson was an influential teacher, and seven of his students went on to win Nobel Prizes: Ernest Rutherford (Chemistry 1908), Lawrence Bragg (Physics 1915), Charles Barkla (Physics 1917), Francis Aston (Chemistry 1922), Charles Thomson Rees Wilson (Physics 1927), Owen Richardson (Physics 1928) and Edward Appleton (Physics 1947).^[7]

^ ^a ^b ^c ^d ^e ^f ^g "Joseph Thomson - The Mathematics Genealogy Project". genealogy.math.ndsu.nodak.edu. Retrieved 31 May 2025.
^ ^a ^b ^c ^d ^e ^f "Joseph John Thomson - Physics Tree". academictree.org. Retrieved 17 July 2025.
^ "J.J. Thomson – Biographical". The Nobel Prize in Physics 1906. The Nobel Foundation. Retrieved 11 February 2015.
^ ^a ^b Cite error: The named reference Profile was invoked but never defined (see the help page).
^ "Nobel Prize in Physics 1906". nobelprize.org. Retrieved 20 February 2025.
^ Cite error: The named reference Jones was invoked but never defined (see the help page).
^ Sengupta, Sudipto (6 April 2015). "Extraordinary Professor: JJ Thomson and his Nobel Prize Factory". Probashi. Durga Puja & Cultural Association (India). Retrieved 7 August 2022. His Nobel Laureate students include Rutherford, Aston, Wilson, Bragg, Barkla, Richardson, and Appleton

[MGP-1] ^ ^a ^b ^c ^d ^e ^f ^g "Joseph Thomson - The Mathematics Genealogy Project". genealogy.math.ndsu.nodak.edu. Retrieved 31 May 2025.

[PhysicsTree-2] ^ ^a ^b ^c ^d ^e ^f "Joseph John Thomson - Physics Tree". academictree.org. Retrieved 17 July 2025.

[Nobel1906-3] "J.J. Thomson – Biographical". The Nobel Prize in Physics 1906. The Nobel Foundation. Retrieved 11 February 2015.

[Profile-4] Cite error: The named reference Profile was invoked but never defined (see the help page).

[5] "Nobel Prize in Physics 1906". nobelprize.org. Retrieved 20 February 2025.

[Jones-6] Cite error: The named reference Jones was invoked but never defined (see the help page).

[7] Sengupta, Sudipto (6 April 2015). "Extraordinary Professor: JJ Thomson and his Nobel Prize Factory". Probashi. Durga Puja & Cultural Association (India). Retrieved 7 August 2022. His Nobel Laureate students include Rutherford, Aston, Wilson, Bragg, Barkla, Richardson, and Appleton

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