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Young J.J. Thomson |
Joseph John Thomson was born in Cheetham Hill, Manchester,
England on 18 December 1856. His father, Joseph James Thomson,
was an antique bookseller and publisher and his mother, Emma
Thomson, came from a family who owned a cotton spinning company.
At the age of 14, J.J., as he came to be known, enrolled at
Owens College in Manchester (which later became the
University of Manchester). At Owens, J.J. studied engineering,
mathematics, physics and chemistry. During his second year, when
he was 16 years old, J.J.’s father died.
In 1876, Thomson was awarded an entrance scholarship to Trinity
College in Cambridge, England and in 1880 he completed his
degree, finishing second in his class. After graduation, Thomson
stayed in Cambridge and was made a Fellow of Trinity. During
this time, J.J. concentrated on studies in physics, and began
experimental work at the Cavendish Laboratory under Lord
Rayleigh. Thomson entered physics at an important point in its
history. Following the great discoveries of the 19th century in
electricity, magnetism, and thermodynamics, many physicists
believed that their science was complete and would yield no new
great discoveries. A year later, Thomson published his first
major paper in the Philosophical Magazine showing that an
electrified sphere, by acting as a current when it moves, would
have an extra mass as a result of its charge. This work was the
first hint of a connection between mass and energy.
Thomson's achievements were recognized by his peers early on, an
in 1884 he was elected a fellow of the Royal Society of London
and appointed to the chair of physics at the Cavendish
Laboratory. On January 22, 1890 J.J. Thomson married Rose Paget.
Rose was a researcher at the Cavendish lab and among the first
generation of women permitted into advanced studies at the
University. J.J. and Rose had two children: George Paget Thomson
became a prominent physicist himself and was later awarded the
Nobel Prize (1937) for proving that the electron was in fact a
wave, and Joan Paget Thomson often accompanied her father in his
travels.
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Joseph John Thomson |
Thomson's most important line of work helped to smash Dalton’s
theory that atoms resembled tiny billiard balls. Thomson
conducted experiments with a newly discovered scientific oddity,
the cathode ray tube (now familiar to most people because of cathode ray
TV and computer screens). Thomson observed that cathode rays, a
strange stream of particles that appeared to fly across a vacuum
tube when an electric current was introduced across it, would
bend in the presence of a magnetic field. Thomson realized that
these strange particles, which he called corpuscles, had a
negative electrical charge and were much less massive than the
atoms from which they came. This discovery showed that atoms
were not solid billiard balls, but were made up of equally
charged positive and negative components. The discovery of J.J.’s corpuscles, now called electrons, caused a sensation in
scientific circles in 1897 and eventually resulted in his being
awarded a Nobel Prize (1906). Thomson’s discovery would also
lead one of his students, Ernest Rutherford, to redefine the
atomic model.
In 1918, Thomson became Master of Trinity
College, Cambridge, where he remained until his death. J.J.
Thomson died on August 30, 1940 and is buried in Westminster
Abbey, close to Isaac Newton.
For more information on the work of J.J. Thomson, visit our
module titled
Atomic Theory I: The Early Days.
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