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Last 10 Posts [ In reverse order ]
Capracus Posted on Nov 1 2011, 02:03 AM
  Back to the Future hoverboard.
http://news.cnet.com/8301-17938_105-201235...defies-gravity/
Capracus Posted on Nov 1 2011, 12:50 AM
  http://en.wikipedia.org/wiki/Magnetic_levitation
El_Machinae Posted on Oct 23 2011, 01:37 PM
  Here's another two tricks with that superconductor (Type 2?) effect!

At minute 3, it's something new. Stuff before that is a repeat of my video one post up.
http://www.youtube.com/watch?v=VyOtIsnG71U

It's awesome!
El_Machinae Posted on Oct 21 2011, 08:21 PM
  You're thinking about this video?

http://io9.com/5850729/quantum-locking-wil...ow-does-it-work
Robittybob1 Posted on Oct 20 2011, 08:04 PM
 
QUOTE (AAA123 @ Oct 20 2011, 04:41 PM)
How does a magnet levitate above a superconducting coil?

According to my understanding:
As the magnet approaches the coil the change in flux linkage through the coil induces an emf in it. This emf causes a current to flow in a direction such that it opposes the change in flux linkage. The magnetic field of the current applies a force on the magnet in the opposite direction to its motion so it levitates. Since it is a superconductor the current still flows in it even though there is no more emf induced as the magnet is at rest.

I have two doubts regarding this concept:

1) If the force is equal to the weight of the magnet then the magnet should continue to fall at a constant velocity.

2) If the force is greater than the weight then when it comes to rest above the coil it should accelerates upwards causing flux linkage to change and reversing the direction of the current so it falls back down causing the process to be repeated.

It would be in a sweet spot where the force of gravity balanced the repulsion of the magnetic fields.
Any closer magnetic field would be stronger so it would rise again. If you look at it there maybe a slight oscillation in the levitated state.

So what keeps the electrons flowing is their momentum (is it conservation of momentum?)
AAA123 Posted on Oct 20 2011, 04:41 PM
  How does a magnet levitate above a superconducting coil?

According to my understanding:
As the magnet approaches the coil the change in flux linkage through the coil induces an emf in it. This emf causes a current to flow in a direction such that it opposes the change in flux linkage. The magnetic field of the current applies a force on the magnet in the opposite direction to its motion so it levitates. Since it is a superconductor the current still flows in it even though there is no more emf induced as the magnet is at rest.

I have two doubts regarding this concept:

1) If the force is equal to the weight of the magnet then the magnet should continue to fall at a constant velocity.

2) If the force is greater than the weight then when it comes to rest above the coil it should accelerates upwards causing flux linkage to change and reversing the direction of the current so it falls back down causing the process to be repeated.
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