News for hackers. Stuff that matters.

A comment on What Happens When You Drop A Magnet Inside A Copper Tube [video]. Parent comment

Re:What Happens When You Drop A Magnet Inside A Copper Tube ... by taliesinb on Monday February 03, 2014 @05:37PM (#7174025)
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 [2] http://www.youtube.com/watch?v=7_ZgiumS41Q

[ Parent | on HN ]
Re:What Happens When You Drop A Magnet Inside A Copper Tube ... by hurowits on Tuesday February 04, 2014 @07:35AM (#7176986)
You might wanna take a look at this video: http://www.youtube.com/watch?v=VyOtIsnG71U
[ Parent | on HN ]
Re:What Happens When You Drop A Magnet Inside A Copper Tube ... by exhilaration on Tuesday February 04, 2014 @10:43AM (#7178092)
Incredible. For anyone watching, make sure you at least go past 2:20 - that's when they pull out the magnetic rail.
[ Parent | on HN ]
Re:What Happens When You Drop A Magnet Inside A Copper Tube ... by IgorPartola on Monday February 03, 2014 @05:48PM (#7174087)
The levitation over a superconductor was the other cool demo that the professor did :).
[ Parent | on HN ]
Re:What Happens When You Drop A Magnet Inside A Copper Tube ... by rbanffy on Monday February 03, 2014 @06:22PM (#7174294)
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...

[ Parent | on HN ]
Re:What Happens When You Drop A Magnet Inside A Copper Tube ... by mjcohen on Monday February 03, 2014 @06:55PM (#7174474)
Ha! When I was in school, we had to push the electrons around by hand! You kids had it easy!
[ Parent | on HN ]
Re:What Happens When You Drop A Magnet Inside A Copper Tube ... by JakeStone on Monday February 03, 2014 @07:16PM (#7174575)
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.

[ Parent | on HN ]
Re:What Happens When You Drop A Magnet Inside A Copper Tube ... by smoyer on Monday February 03, 2014 @08:28PM (#7174889)
I'm declaring a winner here ... the only possible thing that could top that is "through three-foot deep snow".
[ Parent | on HN ]
Re:What Happens When You Drop A Magnet Inside A Copper Tube ... by IgorPartola on Monday February 03, 2014 @08:05PM (#7174787)
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.
[ Parent | on HN ]
Re:What Happens When You Drop A Magnet Inside A Copper Tube ... by fnordfnordfnord on Monday February 03, 2014 @11:13PM (#7175451)
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.
[ Parent | on HN ]
Re:What Happens When You Drop A Magnet Inside A Copper Tube ... by lotharbot on Tuesday February 04, 2014 @12:03AM (#7175618)
http://search.dilbert.com/comic/We%20Didn%27t%20Have%20Zeros (Sept 8, 1992 Dilbert)
[ Parent | on HN ]
Re:What Happens When You Drop A Magnet Inside A Copper Tube ... by Intermernet on Monday February 03, 2014 @06:46PM (#7174419)
Zeroes and Ones? Luxury! In my day we couldn't afford the Ones, we had to make do with just Zeros...
[ Parent | on HN ]
Re:What Happens When You Drop A Magnet Inside A Copper Tube ... by dllthomas on Monday February 03, 2014 @06:37PM (#7174379)
lOl
[ Parent | on HN ]