J.J. Thomson

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J.J. Thomson

J.J. Thomson Biography

Joseph John Thomson (J.J. Thomson) was born on December 18,1856 in Maanchester, England, UK. His father, Joseph James Thomson, ran a specialist bookshop that had been in his family for three generations. His mother, Emma Swindells, came from a family that owned a cotton company. Thomson was interested in science, even when he was a little boy.

About J.J. Thomson

At the age of 14, J.J. became a student at Owens college, the university of Manchester. He studied mathematics, physics, and engineering. Joey's parents hoped that he would become an apprentice engineer with a locomotive company. His father died when J.J. was 16. The fees for engineering apprenticeships were high and his mother could not pay them. So, unfortunately, J.J. was not able to do that. In 1876, at age 19, he won a scholarship that took him to the University of Cambridge to study mathematics. Four years later, he graduated with high honors in his bachelors degree.



While Thomson continued to study at Cambridge, in 1882 he won the Adam's Prize, one of the unversity's most desired after prizes in mathematics. In 1833, he was awarded a master's degree in mathematics.The work that he was awarded with, both the Adam's Prize and his master's degree, had the title, A Treatise on the Motion of Vortex Rings. Although many building blocks have been discovered, Thomson's electron appears to be a truly significant particle that cannot be divided further. In 1906, Thomson was awarded the 1906 Nobel Prize in Physics for his discovery.

When Thomson began his career, he decided he would picture atoms as a smoke ring and let mathematics take it from there since no one knew what atoms looked like. Along with his interest in atoms, Thomson began to have a serious interest in James Clerk Maxwell's equations, which revealed electricity and magnetism to be demonstration of a single force- the electormagnetic force- and had revealed light to be an electromagnetic wave. In 1893, at the age of 36, Thomson published Notes on Recent Researches in Electricity and Magnetism. This book is sometimes called Maxwell's Equations Volume 3 because it was building off of his work.

Beginning his Career...

In Thomson's time, it was known that atoms were involved in some way with electric charges, and that atoms could exist in ionic forms, carrying positive or negative charges. He knew this because in 1834, Michael Faraday made the word "ion" to account for charged electrodes. In 1891, George Johnstone Stoney had made the word electron to represent the essential unit of an electron charge. Although, he did not propose that the electron existed as a particle in its own self. He believed that it represented the smallest unit of charge an ionized atom could have. Atoms were still observed as indivisible.

In 1897, at age 40, Thomson created a now famous experiment with a cathode ray tube. Thomson allowed his cathode rays to travel through air instead of the usual vacuum. He was surprised at how far they could travel before they were stopped. This implied to him that the particles within the cathode rays were many times smaller than scientists had estimated atoms to be! The cathode rays were smaller than atoms!

One Discovery

Then, to estimate the mass of the cathode ray particle and discover whether its charge was positive or negative, Thomson deflected cathode rays with electric and magnetic fields to see the direction they were deflected and how far they were pulled off course. He knew the size of the deflection would tell him about the particle's mass and the direction would tell him the charge the particles carried. He also estimated mass by measuring the amount of heat the particles generated when they hit a target. Thomson used a cloud chamber to establish that a cathode ray particle carried the same amount of charge as a hydrogen ion! With the outcome of these experiments, Thomson came up with three revolutionary conclusions:-Cathode ray particles were negatively charged.-Cathode ray particles were at least 1000 times lighter than a hydrogen atom.-Whatever source was used to generate them, all cathode ray particles were of identical mass and identical charge.

2300 years earlier, Democritus in Ancient Greece had used his intellect to reduce the existence of atoms. Then, in 1808, John Dalton renewed Democritus's idea with his atomic theory. By Thomson's time, scientists were convinced that atoms were the smallest particles in the universe, the essential building blocks of everything.The beliefs were no longer true. J.J. Thomson's experiments proved the existence of a new fundamental particle, much smaller than the atom: the electron. The world will never be the same again.

A Discovery that Changed The World.....

Physicists now research particles smaller than the atom, which they have done ever since. They are trying to discover the building blocks...that make up the building blocks... that make up the building blocks.... of matter!

In 1907, Thomson established, using a variety of methods, that every atom of hydrogen has only one electron.

Although Thomson dicovered the electron, protons and neutrons were yet to be discovered. In 1912, Thomson discovered that the same element could exists with different atomic masses.

Thomson was knighted in 1908, becoming Sir J.J. Thomson. Joesph John Thomson died at the age of 83, on August 30, 1940. His ashes were buried in the Nave of Westminister Abbey, joining other science greats such as, Isaac Newton, Lord Kelvin, Charles Darwin, Charles Lyell,and his friend and former research worker, Ernest Rutherford.

The End of A Successful Journey

Based on his results, Thomson made his famous "plum pudding" model of the atom, which was incorrect. He thought of the atom as a uniformly positively charged 'pudding' which the plums (electrons) orbited. In addition to discovering the electron, Thomson also worked on an invention for chemical analysis- the mass spectrometer.

Thomson became Cavendish Professor of Experimental Physics at Cambridge (first held by James Clerk Maxwell) at the age of 27!


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