Review of EM wave ? particle

1
Review of EM wave ? particle

• EM wave behave as particle
• Proof
• Blackbody radiation. Plank proposes ??? to solve
  ??? problem.
• Photoelectric effect. Einstein proposes ??? in
  order to explain ???.
• Compton Scattering. Try to derive Compton
  Scattering formula and explain why this is a
  proof that photon here behaves as particle.
• Energy (EM wave) converts into matter (particle)
• Pair production.
• When photon is a particle, a wave?

2
Particles (matter) behave as waves and the
Schroedinger Equation

• Quiz 9.23.
• Topics in particles behave as waves
• The (most powerful) experiment to prove a wave
  interference.
• Properties of matter waves.
• The free-particle Schrödinger Equation ? door to
  a different world.
• The Uncertainty Principle.
• The not-unseen observer.
• The Bohr Model of the atom.
• The second of the many topics for our class
  projects.
• Material and example about how to prepare and
  make a presentation (ref. Prof. Kehoe)

today
Thur.
3
The (most powerful) experiment to prove a wave
interference

• Particle or wave, how do I know?
• Particle scattering. Characterized by mass,
  position and momentum.
• Wave interference. Characterized by wavelength,
  frequency, amplitude, phase.
• A double-slit experiment
• A review of the double-slit experiment in optics.
  A nice review article http//en.wikipedia.org/wik
  i/Double-slit_experiment.
• A description of the thought experiment a
  double-slit experiment with electrons.
• What is oscillating? The probability density of
  finding the particle at a certain location and
  time.

4
The Braggs Law

• The Braggs Law for X-rays scattering off a
  crystal surface a powerful tool to study
  crystal structures through diffraction.
• Constructive interference when
• Where m is the order of interference. m 1, 2, 3,

5
The Davisson-Germer experiment
Results Confirmed that the Bragg Law applies to
electrons as well. Electrons interfere.
Electrons behave like a wave.
Ref http//hyperphysics.phy-astr.gsu.edu/Hbase/da
vger.htmlc1
6
Properties of matter waves

• The de Broglie wavelength of a particle
• Frequency
• (review) Wave number and angular
  frequency
• The h-bar constant
• ?
• ?
• Discussion about the velocity on the board.

7
The free-particle Schrödinger Equation

• Waves on a string a mechanical wave
• The wave equation (needs classical mechanics)
• A solution the wave function
• The Electromagnetic waves (Maxwells equations)

And the solutions
8
The free-particle Schrödinger Equation

• The matter waves
• The interpretation of the matter wave function
• The plane wave

9
Review questions

• How do you understand the wave function of
• Please review the mechanical waves you learned in
  intro level physics course. Refresh yourselve
  with wavelength, frequency, amplitude, wave
  energy density, wave phase velocity, wave group
  velocity.

10
Preview for the next class

• Text to be read
• In chapter 4
• Section 4.4
• Section 4.5
• Section 4.6
• Questions
• According to the momentum-position uncertainty
  principle, if you know a particles position
  exactly, what precision can you reach in its
  momentum measurement?
• What is Bohrs atom model? In which what is his
  main postulate? What is the Bohr radius?
• Google electron microscope and read about it.
  Can you connect this instrument with what we
  discuss here?