PHYS 301
Study Guide for Section II
Chapters
4 and 5
Chapter 4 and 5 deal with early quantum theory
(1900--1925). The topics: Black Body Radiation; Photoelectric Effect; De
Broglie Relation; Compton Effect, and the Bohr Model of the atom have been of
paramount importance in convincing scientists to accept and
see the significance of quantum theory. You should understand the history and
the concepts behind these topics and then be able to use the formulas associated
with them to solve problems. Slides 1 -- 88 and 95 -104 on the above link provide a good
review or early quantum theory. Also check the Visual Quantum Mechanics link. Play
with , e.g., the hydrogen emission spectra
experiment. I have linked all the topics below. Use your notes and the
textbook as the guide. Some of the links are elementary and some a little
advanced. They should help supplement your notes and your book.
Ch.5 & 6 Early Quantum Theory:
The
Nature of Light
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300 years ago, scientists did now if light had a
wave or particle nature. How does quantum theory resolve this problem. |
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List phenomena of light that can be
explained by wave or particle nature of light. |
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List phenomena of light that require the
wave nature for their explanation.
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What is a photon? What role does it play in the
photoelectric effect and also in explaining the black body radiation
curve?
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Black
Body Radiation
Read the supplementary notes and appropriate section in your book related to
black body radiation
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How did the experimental black body radiation
curve agree or disagree with the Rayleigh-Jeans Law? |
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What did Planck introduce to come up with his
radiation law? |
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How did the experimental black body radiation
curve agree or disagree with Planck's Radiation Law? |
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How are Wien's diplacemt law and Stefan-Boltzman
law obtain from Planck's Radiation Law? ( Be able to describe the method,
You do not have to reproduce the derivation). |
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Be
able to determine the temperature of a star using Wien's law. |
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Be
able to determine the total energy out put of a star unsung
Stefan-Boltzman law. |
Photoelectric
Effect
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How did Einstein explain the photoelectric effect?
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Be
able to use Einstein's photoelectric equation to calculate, K.E of ejected
electrons, work function, threshold frequency and.or wavelength etc. |
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List everyday applications or some devices that
utilize the photoelectric effect
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If
a stopping potential (V) Vs frequency (f) is plotted, what will be the
slope and Y intercept of the curve. What does the curve, its slope and
intercept prove? |
The
Compton Effect
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What is Compton effect? |
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Write down an expression for the change in
wavelength a photon suffers due to a collision with an electron that was
at rest relative to the lab. What happens to the electron after the
collision? |
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Write down equations based on the laws of
conservation of energy and momentum that govern this collision? |
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Does the Compton effect prove that the photon is a
particle or wave? Be able to explain. |
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Be
able to use the formula that summarizes the Compton effect in problems. |
De Broglie
Relation (Matter Waves)
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What the main idea behind de Broglie's thesis? |
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Write down de Broglie's relation and calculate the
wavelength for an electrons going at v =.5c and 1000 kg car
gong at 62.5 mph? |
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Describe the Davisson-Germer electron diffraction
experiment with the help of a sketch diagram. |
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Be
able to write down Bragg's Law.
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Using Bragg's law, be able to calculate the wave
length of electrons that are incident on a crystal and compare the
result with the wavelength that is obtained using De Broglie
relation. Refer to examples in you notes and the book. What does this
comparison prove. |
The Bohr Model
for Single Electron
Atoms . Electron
Diffraction
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Write down Balmer's
original formula and use it to calculate the wavelengths of the four
hydrogen spectral lines. |
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Transform Balmer's formula into the Rydberg-Ritz
formula. |
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State the three postulates (assumptions) Bohr made
to construct his model of the single electron atom. |
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What is the value and significance of the Bohr
radius? |
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According to the Bohr model how are the emission
and absorption spectra of an atom produced? |
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Does the Bohr atom use the wave or particle nature
of light? |
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What is the reduced mass of an electron and a
proton? How does using the reduced mass instead of the electron mass
affect the Rydberg constant calculated using the Bohr model? |
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What is the significance of the Frank-Hertz Experiment? |
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How is the quntization of angular momentum (L =
nh/2 pi) explained using the de Broglie relation? |
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How does the quntization of L apply to energy
levels of diatomic molecules? ( see page 141) |
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How do ideas from the Bohr model apply to a
harmonic oscillator? (see page 143). |
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What is the Correspondence principle? (see page
144) |
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List some of the successes and
limitations of the Bohr Model.
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