Bohrs Third Postulate

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Bohrs Third Postulate
A single photon is emitted whenever an electron
jumps down from one orbit to another.
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• Why do astronomers often use the terms color and
  temperature interchangeably when referring to
  stars?
• Why did Bohr assume that the electrons do not
  radiate when they are in the allowed orbits?

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Wave Nature of Matter
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De Broglie Wavelength
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Wave-particle duality apply also to matter.
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De Broglies Hypothesis Applied to Atoms
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Quantum Mechanics of Atoms
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The Wave Function and Its Interpolation
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In quantum mechanics the amplitude of a particle
wave is called the wave function and is given the
symbol Y.
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If we are dealing only with one photon At any
point the square of the electric field strength
is a measure of the probability that a photon
will be at that location.
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For a single particle Y2 at a certain point in
space and time represents the probability of
finding the electron at the given position and
time.
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Important there is no way to predict where one
electron would hit the screen. We could predict
only probabilities.
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The main point of this discussion is this if we
treat electrons as if they were waves, then Y
represents the wave amplitude. If we treat them
as particles, then we must treat them on
probabilistic basis.
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The Heisenberg Uncertainty Principle
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The act of observing produces a significant
uncertainty in either the position or the
momentum of electron.
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Position uncertainty of a baseball
What is the uncertainty in position, imposed by
the uncertainty principle, of a 150-g baseball
thrown at 42-1 m/s? Should the umpire be
concerned? Can he use Heisenberg as an excuse?
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Particle in a Box
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Baby-Quiz

• If all objects emit radiation, why dont we see
  most of them in the dark?
• Suppose you were a nineteenth-century scientist
  who had just discovered a new phenomenon known as
  Zeta rays. What experiment could you perform to
  define if Zeta rays are charged particles or e/m
  waves? Could this experiment distinguish between
  neutral particles and an e/m wave?
• If a metal surface is illuminated by light at a
  single frequency, why dont all the
  photoelectrons have the same kinetic energy when
  they leave the metals surface?
• What property of the emitted electrons depends on
  the intensity of incident light?What property of
  the emitted photoelectrons depends on the
  frequency of incident light?