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Quantization

Quantization. In spite of the many successes of classical physics, experiments began to discover phenomena that were difficult to understand. Electron e/m. Cathode ray tube. Electron e/m. Electron e/m. Electron e/m. This experiment established the electron as a particle

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Quantization

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  1. Quantization • In spite of the many successes of classical physics, experiments began to discover phenomena that were difficult to understand

  2. Electron e/m • Cathode ray tube

  3. Electron e/m

  4. Electron e/m

  5. Electron e/m • This experiment established the electron as a particle • The present value of e/m is • e/m=1.76x1011 C/kg

  6. Line Spectra • Recall from optics how a diffraction grating works

  7. Line Spectra

  8. Line Spectra

  9. Charge Quantization

  10. Charge Quantization

  11. Charge Quantization • The oil drop experiences a downward gravitational force (mg) and an upward frictional force (bv) • The terminal velocity of the falling oil drop is • The viscous force is given by Stokes’ law with • The mass is given by

  12. Charge Quantization • With the addition of an electric field we have • The terminal velocity for rising is just • And thus

  13. Charge Quantization • Millikan observed that the charge on the drops was always ne where n is an integer • The present value of e is 1.602x10-19C

  14. Charge Quantization • Millikan’s measurement was not without controversy • Some charge he only used the “best” data • This is almost exactly right & the best one I ever had!!! • Exactly right • Publish this Beautiful one • Error high will not use • Too high by 1½% • His graduate student came up with the idea of using oil (but was not co-author on the paper)

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