Physics research: Interesting questions, Interesting Independent Lab projects

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Physics researchInteresting questions,
Interesting Independent Lab projects

• Daniel W. Koon
• Spring 2005

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Goals of this talk

• Describe some general subtopics of physics
• Solid State physics
• Optics
• Describe some interesting research questions,
  including my own research
• Suggest some Independent Lab project ideas

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Structure of this talk

• Solid state physics
• Research areas
• project ideas
• Optics
• Research areas
• project ideas
• Miscellaneous project ideas

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Solid state physics charge transport

• Charge transport
• the measurement of resistivity and Hall effect
• a cheap sub-atomic microscope
• A cheap sub-atomic microscope How so?
• Its cheap
• It explores how the molecules of the material
  treat their electrons

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Resistivity, r

• Resistance, R measures how an object resists the
  flow of current
• Resistivity, r measures how a material resists
  the flow of current
• So, (SAT flashback)
• r R Density mass
• G(size,shape) R

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The Hall coefficient the other charge transport
quantity

• The Lorentz force
• Gives rise to a Hall voltage
• (The Hall effect is the bending of current due to
  a magnetic field.)

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Punchline charge transport as a cheap subatomic
microscope

• Since
• we can deduce the microscopic quantities by

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Koons solid state interests

• I. The phenomenology of charge transport
  measurement
• Error analysis What do you measure when you
  measure r, RH?
• Is there a best sample shape?

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Error analysis How to do it

• Using computer to model current flow in the
  specimen
• To compare different geometries
• To test effects of thickness
• Using a discrete-resistor model in the laboratory
• To test linearity of the effect

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Koons solid state interests

• II. Applying charge transport measurement to
  specific materials
• Hydrogen absorption in rare-earth/Pd bilayers
• Challenges
• Rare earths corrode in O2.
• Pd overlayer stops corrosion, allows H2
  absorption.
• Pd is a much better conductor.
• So, how do you measure the properties of just the
  RE?

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Interesting Solid State questions

• Is the effect of resistive inhomogeneities
  linear? Is it additive (If I poke twice as big a
  hole in a film does it produce twice the effect?)
• Can we simultaneously measure the resistivity and
  transmittance of a hydriding or corroding film?
• How does the resistivity, Hall coefficient of a
  material change as it freezes/thaws?

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Optics Biomaterials and more

• Photonic Polar bears?
• Solar efficient butterflies?
• Ulexite (TV rock)
• Scarlet macaws

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• The hairs of the polar bear are transparent light
  pipes that direct ultraviolet light to its skin
  -- which is guess what color? Black! So whats
  white and black and warm all over? A polar bear
  under the arctic sun.
• Paul G. Hewitt, Conceptual Physics, 6th Edition,
  1989, p. 501

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• Aristotle maintained that women have fewer
  teeth than men although he was twice married, it
  never occurred to him to verify this statement by
  examining his wives mouths.
• Bertrand Russell

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Optical attenuation spectrumpolar bear hair
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FOUL(UP)A Fiber-Optic Ursine Link (Universal
Prototype)for telecommunicationsD. W. Koon and
C. L. Jahncke, Physics Dept., St. Lawrence
University

• ABSTRACT We have constructed what we believe
  is the first prototype of a fiber-optic link to
  use the hair of an Arctic mammal. The potential
  advantages of ursine fiber technology over
  conventional technology are discussed.
• http// it.stlawu.edu/physics/clj/foulup.html

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Interesting Optics questions

• Polar bear hairs as optical fibers?
• Reid Hutchins 98
• Morpho butterflies Does iridescence serve as a
  solar panel or a sunblock?
• Andy Crawford 99
• Ulexite (TV rock) Is there cross talk in the
  fiber optic bundles?
• Jay OBrien 98
• The scarlet macaw Thin-film iridescence, or
  diffraction grating, or what?

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Miscellaneous interesting questions