Sir J'J' Thomson

1
Sir J.J. Thomson
Pioneer In Modern Physics

2
Personal Biography

• Born Cheetham Hill, Great Britain, December 18,
  1856
• Enrolled at Owens College, Manchester, in 1870,
  and in 1876 entered Trinity College, Cambridge as
  a minor scholar.
• He became a professor of experimental physics at
  Cambridge.
• Wrote Treatise on the Motion of Vortex Rings
  which won him the Adams Prize in 1884.
• In 1896 he came to America to give lectures at
  Princeton University.
• Died on August 30, 1940.

3
Interesting Facts

• Won the Nobel Prize for Physics in 1906.
• He was knighted in 1908.
• Became a professor at the age of 27 as professor
  of physics at Trinity College, Cambridge.
• Named professor at Cavendish Laboratory in the
  same year he became a professor.
• Seven of Thomsons students, including his son,
  won the Nobel Prize for Physics.
• Because of his dedication and discoveries in the
  field of subatomic particles, Great Britain has
  dominance in this field.
• He was awarded the honor of burial in Westminster
  Abbey.

4
Atomic Discovery

• In 1897, Thomson concluded that all matter
  contains particles that are much less massive
  than the atoms that they are a part of.
• He originally named these subatomic particles
  corpuscles, but they are now called electrons.
• This discovery came about while he was testing
  the unusual nature of cathode rays, which appear
  when an electric current is sent through a
  vacuum.
• Thomson came up with a new vacuum technique, and
  was able to come up with an argument that the
  rays were made up of negatively charged particles.

5
Experimental Setup

• The cathode ray tube (CRT) that Thomson used in
  his experiments was about a meter long and built
  by hand.
• The tube was vacuum sealed
• Two plates in the middle of the CRT were
  connected to a battery to create a strong
  electrical field. The cathode ray passed through
  this field.
• The cathode rays bent toward the positively
  charged plate.
• They bent because cathode rays were electrically
  charged.
• The results indicated that a cathode ray was a
  stream of negatively charged particles.
• He made his discovery in 1894.

6
Uses For the Electron

• Modern ideas and technologies based on the
  electron, leading to television and the computer
  and much else, evolved through many difficult
  steps. Thomson's careful experiments and
  adventurous hypotheses were followed by crucial
  experimental and theoretical work by many others
  in the United Kingdom, Germany, France and
  elsewhere.

7
Thomsons Atomic Model

• After discovering the electron, J.J. Thomson
  developed his plum pudding model of the atom.
• He realized that neutral atoms must have equal
  amounts of positive and negative charge.
• His model shows negative charges as plums and
  positive charges as the pudding.