Sir Joseph John Thomson OM PRS (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. 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.
Thomson was awarded the 1906 Nobel Prize in Physics for his work on the conduction of electricity in gases.
Publications:
- Applications of dynamics to physics and chemistry
- Conduction of electricity through gases
- The Corpuscular Theory of Matter
- Electricity and Matter
- Elements of the Mathematical Theory of Electricity and Magnetism
- On the Light Thrown by Recent Investigations on Electricity on the Relation Between Matter and Ether
- Rays of Positive Electricity and their Application to Chemical Analysis
- A Text-Book of Physics
- Carriers of negative electricity [Nobel Lecture]