J.J. Thomson was a British physicist who won the 1906 Nobel Prize in Physics for his work on the conduction of electricity in gases. Some of his key accomplishments included discovering the electron in 1897 through experiments with cathode ray tubes, determining the mass-to-charge ratio of electrons, and proposing the "plum pudding" model of the atom. He had a long and distinguished career as a physicist, holding positions at Cambridge University and lecturing widely in the United States. Thomson made many contributions to the field and influenced several students and assistants who went on to also win Nobel Prizes.

1. Group Activity On
Biography Of A Nobel Prize Winning Physicist –
J.J.Thomson
Submitted to :
Dr. N.L. Mathakari
Dr. A.B. Deore
Submitted by :
Mr. Anish Agarwal (101018)
Mr. Aditya Agarwal (101019)
Mr. Akkahshh Agarwaal (101020)
Mr. Anshul Agarwal (101021)
MIT-WORLD PEACE UNIVERSITY , KOTHRUD
PUNE - 411038

2. SIR JOSEPH JOHN THOMSON
• Birth : 18 December 1856 in Manchester , England.
• Father - antique bookshop
• Mother – family’s textile company
• Brother - two years younger than him.
• Wife : Rose Paget and had one son and one daughter.
• Age 14 – Owens College ( now University Of Manchester )
• Age 20 – Trinity College, Cambridge to obtain B.A. (Mathematics) , M.A.
(Mathematics).
Education And Personal Life

3. Career
• Age 28 – Cavendish Professor Of Physics at University of Cambridge.
• Nobel Prize in 1906 – Conduction of electricity by gases.
• Lectures at Princeton And Yale University – Discharge of electricity through gases
• Discovered the electron
• Elected as a Fellow of the Royal Society
• thomson (Th) – unit of mass-to-charge ratio
• JJ Thomson Avenue – University of Cambridge campus
• Various awards and honors – Adams Prize, Franklin Medal, etc.

4. The Cathode Ray Tube Experiment : Discovery of the
electron
• Cathode ray tubes are sealed glass tubes which have been evacuated to create vacuum. A high voltage is applied at the
two pieces of metal at one end of the tube which causes a beam of particles to flow from the cathode to the anode.
• The tubes are called “cathode ray tubes” because the particle beam originates at the cathode.
• The ray is detected by painting a special coating of phosphorus onto the other end of the tube. It emits light when
impacted by cathode ray.
• What is the ray made up of ? Does the ray have electrical charge ?
• To test it’s properties, Thomson placed two oppositely charged plates around the cathode ray. Instead of going straight
through, the ray was deflected away from the negatively – charged plate and it was attracted towards the positively
– charged plate. Thomson also placed two magnets on either side of the tube and observed the same result.

5. • The results helped him to determine the mass-to-charge ratio of the particles.
• He repeated the experiments using different metals and found that the properties of the cathode ray remained
constant irrespective of the metal used.
• Thomson made the following CONCLUSIONS from his experiment :
1. The cathode ray is composed of negatively charged particles.
2. The particles that make up cathode rays are a 1000 times smaller than hydrogen atom.
3. All different metals give off cathode rays.
• Atoms have tiny, negatively charged particles inside them – “ELECTRONS”
• On the whole, atoms are electrically neutral. Hence, there must be positive charge in the atom to balance out the
electrons.
• This lead to the Plum Pudding Model of an Atom.
The Cathode Ray Tube Experiment : Discovery of the
electron

6. Contributions
• Highly gifted teacher.
• Six research assistants - Nobel Prize in physics
• Two research assistants - Nobel Prize in chemistry.
• Son, George Paget Thomson - Nobel Prize in physics - proved the wave-like
properties of electrons.
• 1905 - natural radioactivity of potassium.
• 1906 - hydrogen has a single electron per atom.
• Invention of Mass Spectrometer.
1. Measuring size of nanoparticles and hence calculate density of particle
leading to finding the properties and behavior of the particle.
2. Looking for toxins (DEG-Diethylene Glycol) in toothpaste.
3. Looking for pesticides in food.
• Atom as a Plum Pudding – famous but incorrect model – uniformly spread and
positively charged pudding with electrons embedded in it.

7. BIBLIOGRAPHY
• https://en.Wikipedia.org/wiki/J._J._Thomson
• https://www.famousscientists.org/j-j-thomson/
• https://www.nobelprize.org/nobel_prizes/physics/laureates/1906/tho
mson-facts.html