Wednesday 913

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3/36 Wednesday 9/13
Problem Set PS 0 Due Today PS 1
Friday Today Atomic spectra Double slit
experiment Lab today in room TCL
104B Review Wednesdays at 900 PM TCL 104B

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Heat CapacityatLow Temperature

• At high temperature
• Cv 3 R
• At low temperature
• Cv depends on T
• Classical Theories cannot
• explain

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Gas spectra
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Spectroscopy
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Spectra
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Hydrogen gas spectra
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Bohrs Assumptions (1913)

• I - atoms can exist in stationary states without
  radiating energy
• II - Transitions between these states can occur
  by absorption or emission of radiation
• III - Angular momentum is quantized

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Energy is quantized
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Transition between energy levels
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Spectra from Bohr model
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Correction

• We need to consider that the rotation is around
  the center of mass. Therefore we need to
  exchange the mass of the electron by the reduced
  mass

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Wave property

• Interference of waves

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Wave property

• Interference of waves

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Electron interference (1961)

• Modern experiment with electrons

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Interference

• In a modern experiment (1989) with electrons, one
  can shoot one electron at the time or all at
  once. The final pattern is the same
• Tonomura, A., Endo, J., Matsuda, T, and Kawasaki,
  T, Am. J. Phys., 57,117-120 (1989)