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A Presentation by Bernard Nuar , Josh BOlton , and Justyn Day

The Discovery of the Electron. A Presentation by Bernard Nuar , Josh BOlton , and Justyn Day. Cathode Ray Tube. Inventor: Karl Ferdinand Braun 1897 Specialized vacuum tube The cathode ray produced a bright green light. How does it work?.

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A Presentation by Bernard Nuar , Josh BOlton , and Justyn Day

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  1. The Discovery of the Electron A Presentation by Bernard Nuar, Josh BOlton, and Justyn Day

  2. Cathode Ray Tube • Inventor: Karl Ferdinand Braun 1897 • Specialized vacuum tube • The cathode ray produced a bright green light How does it work? • What was the composition and properties of this mysterious ray?

  3. The Initial Question • How did the cathode ray interact with the solid cross? • Did these cathode rays have particle or wave like properties? • Made his own specialized Crookes tube • Maltese Cross What does this mean? Therefore, the cathode ray has particle like behavior! Sir William Crookes (1832-1919)

  4. Magnetic fields Julius Plücker (1801-1868) Jean Baptiste Perrin (1870-1942) • Discovered that cathode ray was affected by magnetic forces • The beam is deflected towards the positive end of the magnet • Perrin is given credit for having discovered that the particles that made up the cathode ray were negatively charged

  5. Heinrich Hertz • Found that the electron passed through thin gold sheets and illuminated on the other side • First to apply an electric field to manipulate rays path • Failed to manipulate the rays with electric fields. • Brought the gold sheet observation to Thomson’s attention

  6. J.J. Thomson • Regarded as father of the electron • Proved the electron is manipulated by electric fields with lower pressures, which Hertz failed to do • How did he do this? • He replicated and confirmed the results of previous experiments • Calculated the charge to mass ratio of the electron

  7. J.J. Thomson’s cathode • With an electric field • Without an electric field

  8. E/M Derivation • N: number of particles in a cross section of the beam • m: Mass of the particle • v: Velocity • W: kinetic energy of the particle Q=Ne • H: Magnetic field • ρ: Radius of curvature • e: Charge of an electron • I: Current • Q: quantity of electricity carried by the particles What were his findings? e/m = 1.7 x 10^7 About 1/1700 the ratio of Hydrogen!

  9. Thomson’s Theories • Three theories based on experimental observation • Cathode rays are charged particles, “corpuscles” • These corpuscles were constituent of atoms • These corpuscles are the only constituents of atoms (was later proven wrong) The name corpuscles was later replaced with the term electron

  10. Impact of the Findings • The cathode ray was composed of electrons with particle like properties • The electron charge to mass ratio was smaller than the hydrogen atom • It had a negative charge • There must be an opposite charge to maintain electrically neutral atom • Made possible the Plum Pudding model of the atom • It made possible new technologies and advancements in scientific fields

  11. What this discovery gave us: The electron is very important for many things we all use: • Emergence of new sciences made possible: • Quantum Physics • Large Particle Accelerators • Modern Chemistry

  12. Questions

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