4 ms·

You can also think of it as magnetic flux lines encountering "drag" as they pass through conductors. The limiting behavior of this view is in type II supercond

You can also think of it as magnetic flux lines encountering "drag" as they pass through conductors. The limiting behavior of this view is in type II superconductors, which entirely "pin" flux lines -- they present an effectively infinite resistance to the movement of flux lines. That's why a magnet levitates over such a superconductor. [1] You can even image these "vortices" directly [2] [1] http://en.wikipedia.org/wiki/Flux_pinning http://en.wikipedia.org/wiki/Flux_pinning [2] http://www.youtube.com/watch?v=7_ZgiumS41Q http://www.youtube.com/watch?v=7_ZgiumS41Q

IgorPartola 13y ago
The levitation over a superconductor was the other cool demo that the professor did :).
- rbanffy 13y ago
  Lucky kids. When I was in school, the only commercial superconductors were liquid Helium cooled Niobium-Titanium alloys, something not many classrooms could handle. ;-) Luckily, when I got to programming, we already had zeroes and ones. Imagine our predecessors who had to do it with uppercase o's and lowercase l's...
  - dllthomas 13y ago
    lOl
  - Intermernet 13y ago
    Zeroes and Ones? Luxury! In my day we couldn't afford the Ones, we had to make do with just Zeros...
  - mjcohen 13y ago
    Ha! When I was in school, we had to push the electrons around by hand! You kids had it easy!
    - JakeStone 13y ago
      You guys had electrons? We had to use scotch tape on a bunch of quarks and give them a half spin and then push them. Uphill. Both ways.
      - smoyer 13y ago
        I'm declaring a winner here ... the only possible thing that could top that is "through three-foot deep snow".
  - IgorPartola 13y ago
    I forget what type we used but it was cooled by liquid nitrogen. That prof. used lots of magnets and superconductors in his research, some cooled by Helium-3. Now that stuff is expensive.
    - fnordfnordfnord 13y ago
      The high-temperature ones were probably Yttrium-Barium-Copper-Oxides (YBCO) I've seen this demo done with them. The magnet's motion is almost undetectable, they appear suspended in the copper pipe until they start to warm up.
  - lotharbot 13y ago
    http://search.dilbert.com/comic/We%20Didn%27t%20Have%20Zeros http://search.dilbert.com/comic/We%20Didn%27t%20Have%20Zeros (Sept 8, 1992 Dilbert)
hurowits 13y ago
You might wanna take a look at this video: http://www.youtube.com/watch?v=VyOtIsnG71U http://www.youtube.com/watch?v=VyOtIsnG71U
- exhilaration 13y ago
  Incredible. For anyone watching, make sure you at least go past 2:20 - that's when they pull out the magnetic rail.

IgorPartola 13y ago

The levitation over a superconductor was the other cool demo that the professor did :).

rbanffy 13y ago
Lucky kids. When I was in school, the only commercial superconductors were liquid Helium cooled Niobium-Titanium alloys, something not many classrooms could handle. ;-) Luckily, when I got to programming, we already had zeroes and ones. Imagine our predecessors who had to do it with uppercase o's and lowercase l's...
- dllthomas 13y ago
  lOl
- Intermernet 13y ago
  Zeroes and Ones? Luxury! In my day we couldn't afford the Ones, we had to make do with just Zeros...
- mjcohen 13y ago
  Ha! When I was in school, we had to push the electrons around by hand! You kids had it easy!
  - JakeStone 13y ago
    You guys had electrons? We had to use scotch tape on a bunch of quarks and give them a half spin and then push them. Uphill. Both ways.
    - smoyer 13y ago
      I'm declaring a winner here ... the only possible thing that could top that is "through three-foot deep snow".
- IgorPartola 13y ago
  I forget what type we used but it was cooled by liquid nitrogen. That prof. used lots of magnets and superconductors in his research, some cooled by Helium-3. Now that stuff is expensive.
  - fnordfnordfnord 13y ago
    The high-temperature ones were probably Yttrium-Barium-Copper-Oxides (YBCO) I've seen this demo done with them. The magnet's motion is almost undetectable, they appear suspended in the copper pipe until they start to warm up.
- lotharbot 13y ago
  http://search.dilbert.com/comic/We%20Didn%27t%20Have%20Zeros http://search.dilbert.com/comic/We%20Didn%27t%20Have%20Zeros (Sept 8, 1992 Dilbert)

hurowits 13y ago

You might wanna take a look at this video: http://www.youtube.com/watch?v=VyOtIsnG71U http://www.youtube.com/watch?v=VyOtIsnG71U

exhilaration 13y ago
Incredible. For anyone watching, make sure you at least go past 2:20 - that's when they pull out the magnetic rail.