Mesmerising - Page 1
Forum section: electronics / general

author: IanB
author_rank: Super Contributor
timestamp: February 06, 2014, 03:48:16 am
content: Everyone's probably seen this video since it went viral, but in case you haven't here it is:I just can't get bored with it.It's where physics blows your mind.

author: BravoV
author_rank: Super Contributor
timestamp: February 06, 2014, 04:01:48 am
content: Curious if this is done in zero gravity, will the magnet stay floated in the middle of the tube ?

author: c4757p
author_rank: Super Contributor
timestamp: February 06, 2014, 04:02:56 am
content: Quote from: BravoV on February 06, 2014, 04:01:48 amI suspect it would probably be somewhat well coupled to the tube.

author: IanB
author_rank: Super Contributor
timestamp: February 06, 2014, 04:03:37 am
content: Quote from: BravoV on February 06, 2014, 04:01:48 amThere is no force on the magnet if it isn't moving. So a stationary magnet will behave like a stationary non-magnet.

author: BravoV
author_rank: Super Contributor
timestamp: February 06, 2014, 04:05:20 am
content: Another type of magnet attraction that is mind blowing as well, levitron, tons of it in youtube, this one from nurdrage.

author: scientist
author_rank: Frequent Contributor
timestamp: February 06, 2014, 05:15:23 am
content: Quote from: BravoV on February 06, 2014, 04:01:48 amI'd like to see elevators using this phenomenon. Or accelerometer readings from on the magnet as it falls.

author: smashedProton
author_rank: Frequent Contributor
timestamp: February 06, 2014, 05:48:12 am
content: Quote from: BravoV on February 06, 2014, 04:01:48 amIt would behave like anything else, it would appear to have an unnatural longitudinal inertia than normal though

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 06, 2014, 07:31:14 am
content: It's funny that he spins the magnet, because although it looks fun, it doesn't actually do anything (well, the square magnet should have an octupole moment, but that will be very small). A tight fitting magnet is much more impressive; one nearly the ID of the pipe would sink at inches per second!I've had the opportunity to play with NdFeB magnets over 999 fine silver bars; they slide so slowly, they actually tumble when the surface is at a steep enough angle (past 70 degrees or so).Thickness is as important as conductivity; a thick aluminum bar is almost as slow as an average copper bar. Having both (like the silver bar) is really cool.Related:http://mysite.du.edu/~jcalvert/tech/faraday.htmTim

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: February 07, 2014, 12:12:43 am
content: Quote from: T3sl4co1l on February 06, 2014, 07:31:14 amI wondered about that - I wonder if it may improve stability or help maintain the vertical orientation

author: warp_foo
author_rank: Unknown
timestamp: February 07, 2014, 01:30:13 am
content: Quantum locking:

author: BravoV
author_rank: Super Contributor
timestamp: February 07, 2014, 01:35:07 am
content: Quote from: warp_foo on February 07, 2014, 01:30:13 amDamn ... I could spend hours playing with that thing.

author: BravoV
author_rank: Super Contributor
timestamp: February 07, 2014, 01:46:40 am
content: Just knew this thing does double levitation.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 07, 2014, 02:30:15 am
content: It's a neat demonstration, by the way, of the AC losses of superconductors. They may be zero ohms DC, but as soon as it starts changing, losses appear. In the high frequency limit, it's also noteworthy that superconductors don't change visible appearance, i.e., there's no effect in the 100THz+ band.Type I superconductors don't trap flux tubes, but they do still exhibit kind of strange losses. The best resonators are niobium reosnators for particle accelerators, with operating frequencies of 100MHz to a few GHz and Qs in the 2 x 10^8 range (IIRC..?). In other words, they actually take human timescales for the resonance to dissipate. The surface finish is very important, but apparently more of a matte finish is better than a perfectly polished surface, or something like that. Subtle physical things that aren't well understood.Tim

author: scientist
author_rank: Frequent Contributor
timestamp: February 07, 2014, 03:19:33 am
content: Quote from: warp_foo on February 07, 2014, 01:30:13 amNever understood why they use the word quantum for that. Yes, it is "quantum" in that it is locking a quantity of molecules in one place relative to a magnetic field, but it's not quantum in the way that they want it to sound like it is...Take, for example, the Verizon "quantum speed" ads. Clearly, quantum is just a buzzword here, because it's fairly obvious Verizon isn't using quantum entanglement to transmit information.

author: BravoV
author_rank: Super Contributor
timestamp: February 07, 2014, 03:22:25 am
content: Quote from: scientist on February 07, 2014, 03:19:33 amCause it sells.

author: warp_foo
author_rank: Unknown
timestamp: February 07, 2014, 04:05:48 am
content: Quote from: BravoV on February 07, 2014, 03:22:25 amSounds better than flux pinning, I suppose...