Tesla Tales

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Tesla Tales

• Carlos R. Villa
• National High Magnetic Field Laboratory

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NHMFL Overview

• One Of Three National Labs In The Southeast U.S.
• One Of Nine High Magnetic Field Labs In The World
• Only One In Western Hemisphere
• Largest And Highest Powered In The World

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Center for Integrating Research Learning

• Educational component of NHMFLs grant
• RET programs
• 6 weeks
• 3600 stipend
• REU also available
• K-12 education outreach
• 9,000 students visited this school year
• Professional development
• Workshops and conferences

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Magnet Review

• Gauss
• Measurement Of Magnetic Field
• Named For Carl Friedrich Gauss
• Tesla
• Measurement Of Larger Magnetic Fields
• Named For Nikola Tesla
• 10,000 Gauss 1 Tesla

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Tesla Tales

• Magnetism
• Ferromagnetic, paramagnetic, diamagnetic
• 1820 Revolution
• Oersted Ampere
• Faradays laws of induction
• Lenzs Law
• Free electron theory of conduction
• BCS theory of superconductivity

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Magnetism

• Motion of electrons create magnetic fields
• In some atoms, spins cancel out
• Pauli exclusion
• Magnetic domains
• In magnets lined up
• Whenever all electrons spin the same direction
  magnetic field is produced

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Ferromagnetism Permanent Magnets

• Electrons tend to line up in groups (Domains)
• Domains reinforce other domains
• Turn material magnetic
• Examples Refrigerator Magnets, Bar Magnets,
  Magnetite, Horseshoe Magnets, Hematite, etc
• Field can be lost
• Curie Point
• Electric Current
• Degaussing
• Bang It

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Ferromagnetism Temporary Magnets

• Domains temporarily aligned
• Will keep magnetic field until tampered
• Examples
• Paperclips, scissors, staples, thumb tacks, pins,
  screwdrivers, refrigerator door, car doors, etc
• Anything that is magnetic, but will not keep its
  field

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Paramagnetism Temporary Magnets

• No force aligning domains
• Randomly distributed
• Domains temporarily aligned by strong field
• Will lose magnetic field when original field is
  removed
• Examples Plastics, aluminum can, copper wire,
  gold jewelry, tungsten, etc

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Diamagnetism The Anti-Magnets

• Domains temporarily aligned by strong field
• Will align in order to oppose original field
• Faradays second law of induction
• When a material whose atoms do not normally
  have a magnetic field is placed in a strong
  field, their electrons will adjust in such a way
  as to create their own magnetic field opposing
  the external one.

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Ferromagnetism Lab Magnetic Fields

• Magnets attract and repel
• Seeing fields
• Bar magnet
• As many compasses as possible

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Ferromagnetism Lab Temporary Magnets

• Paper clips
• Argument driven inquiry
• How long will temporary magnets hold?
• 18 months!
• Do they have poles?
• They attract and repel!
• Can they be unmagnetized?
• Yes, but they can also hold fields!

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Ferromagnetism Lab Compass Creation

• Allow It To Float
• Must Turn Freely
• Needle
• Petri Dish
• Coffee Stirrer
• Water
• Permanent Magnet

• Magnetize An Item

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Diamagnetism Lab

• Superconductors are diamagnetic
• YBCO Works Well
• Kit Available From Colorado Superconductor Inc.

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1820 Oersted Discovery

• An electrical current can create a magnetic field
• Oersted set up lecture demonstration
• Used battery to supply current
• Showed compass needle deflecting near the wire

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Oersted Lab

• Deflect a compass needle
• Battery
• Aluminum foil
• Compass
• Wire
• Assorted other items
• Place the compass
• Above the wire
• Below the wire

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1820 Amperes Law

• Moving electrical charges produce magnetic fields
• Simple experiment
• Two straight wires
• Current passed through
• Wires bowed toward or away
• Led to electromagnets

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Ampere Lab

• Materials
• Copper wire
• Iron rod (or nail)
• Battery
• Extensions
• 2 batteries
• In line?
• Aluminum, wooden rod
• Will they work?

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Ampere Lab Part II

• Right hand rule
• Direction of field (Biot-Savart Law)
• Poles (Winding direction)
• Use compass
• Variables
• Neatness
• Number of winds
• Wire gauge
• Battery strength

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1831 Faradays Laws

• A change in magnetic field produces an electric
  current
• Induction
• Magnetic flux The change needed to induce
  current

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Faraday Lab

• Use copper wire to attach LED lights on a plastic
  pipe.
• Drop NIB magnet through pipe (and through copper
  wires)
• Induction of electricity

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1835 Lenzs Law

• An induced current in a wire (by flux) will flow
  to create a field that opposes the flux
• Eddy currents created
• Used in magnetic braking systems
• Rollercoasters

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Lenz Lab

• Changing Magnetic Flux Produces An Induced
  Electric Field
• Copper Tube, NIB Magnet
• Eddy Currents

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1900 Free Electron Theory

• Electrical conduction in a solid is caused by the
  bulk motion of electrons
• Each metal atom contributes an electron that is
  free to roam
• Voltage briefly accelerates the electrons
• Resistance

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Free Electron Theory Lab

• Current electricity
• Electrons flow through a wire
• Slow movement
• Circuit needed
• Complete circuits using Alien Ball
• Turn on the light bulb
• Turn on two light bulbs
• Create more advanced circuits
• Parallel series

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1957 BCS Theory

• BCS Bardeen, Cooper, Schreiffer
• At low temperatures, some metals lose resistance
• Atoms nearly stationary
• Superconductivity results from the formation of
  Cooper pairs (Two electrons acting as a single
  particle)
• Flow along single intertwined mass
• Results in rapid flow of electrons

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BCS Lab

• Repeat Ampere lab
• Measure resistance with digital multimeter at
  each step
• Raise temperature with hot water
• Lower temperature with ice water
• Lower temperature with liquid nitrogen
• Always adhere to safety guidelines

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Additional Resources

• Stop Faking It Electricity Magnetism
• Bill Robertson

• Driving Force The Natural Magic of Magnets
• James D. Livingston

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Additional Resources

• A Short History of Nearly Everything
• Bill Bryson

• The Nature of Science
• James Trefil

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Additional Resources

• Hidden Attraction The Mystery History of
  Magnetism
• Gerrit L. Verschuur

• The Cold Wars A History of Superconductivity
• Jean Matricon Georges Waysand

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Additional Resources

• http//education.magnet.fsu.edu
• MagLab Alpha Science, Optics, You other
  curriculum
• MagLab audio slideshows
• RET Program
• K-12 Programs

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Thank You

• Carlos R. Villa
• National High Magnetic Field Laboratory
• villa_at_magnet.fsu.edu 850-644-7191