Magnetic Demonstations

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Magnetic Demonstations

• Magnetic Interactions
• Ferro-Magnets very strong attraction
• Examples Iron, steel, nickel.
• Eddy-Current weak damping force
• Examples any conductor

• Dia-magnets very weak repulsion
• Examples water droplet levitating frog
• Much stronger in Superconductors

Water droplet and frog levitating in a very
strong (10 20 Tesla magnet. (10 T is 200,000 x
the field of the earth.)

• Eddy Current Damping
• Magnet induces eddy-currents in metals
  (conductors).
• Eddy-current generate magnetic fields that repel
  and slow (oppose) the magnet.
• Effect stronger for
• Magnet closer to conductor.
• Thicker conductor.
• Better conductor
• Copper (Cu) rCu 1.7 x10-6 W-cm
• Aluminum (Al) rAl 1.6 x rCu
• Stainless Steel r 35 x rCu

• FerroFluid
• Consists of Ultra-small ferro-magnetic particles
• Particles tend to stack along magnetic field
  lines
• Applications
• Adjustable shock absorbers
• Friction reduction

Particles stack in magnetic field. FerroTec
Corporation
Solid vane stops quickly. Vane with loops
stops. Vane with teeth stops slowly.
Ferro fluid has ultra small-magnetic particles
suspended in a fluid (like fat globules in
milk) 85 carrier, 10 surfactant, 5 magnetic
solid
Eddy-current generate magnetic fields that repel
and slow (oppose) the magnet.