Magnets

[Hamish]

Thanks, David-

Gauss rifles are fascinating too. I always thought they worked using electromagnets, not "plain-old" magnets.

That's really fascinating. It took me a little while to see why it's not a perpetual motion machine. Tell me if I'm right - in layman's terms, you'd say that keeping the marble 5/8th of an inch fromt he square magnet is *stored energy?* int he sense that that ball wants to "fall" onto the magnet?

I was sceptical when I saw David's first post. Of course there should have been two ball bearings after each magnet. There is only energy in the system if for each magnet there is a ball bearing not in the "ground state" (lowest possible potential energy). By spacing the ball bearings such that each is held in place by the magnet behind but not touching it, you can store potential energy in the system. In laymans terms, your description was essentially correct.

Back to the subject of big magnets, I worked with a guy who built an electron spectrometer out of two 1 Tesla permanant magnets. It worked by bending the paths of electrons dependant on their velocity. We had to store the thing at least 3 metres from any monitor screens or magnetic storage media. When it came to putting the thing inside a vacuum chamber, he seemed to forget that the chamber was made of steel. It took three men and a big lever about half an hour to get the thing off the chamber wall.

 

[Brian]

Just a suggestion, you can maybe get better prices on eBay, maybe. I think there's a bunch of people out there with garages full of them, so the price is dropping. I got a 1"X1"X1" cube for $16.00 including postage.

Yeah... http://www.wondermagnet.com/crush.html Ouch!

info on the disc

Composition: NdFeB
Shape: disc
Coating: Nickel Plate
Dimensions: 2" dia X 1" thick
Br max: 12,100 Gauss
Bh Max: 35 MGOe

Wow!

 

[ceptimus]

There are some really powerful magnets - of the 'injure yourself if you're not very careful' type inside computer hard disk drives.

If you have a broken drive, or an old low capacity one you don't want anymore, take it apart and get the magnets out. The magnets are on either side of the mechanism that moves the read/write head, to the different track positions (the mechanism swings the heads over an arc of maybe 60 degrees.

The magnets are arranged so the magnetism is almost totally confined within the mechanism - so you won't realise how strong they are till you take it apart.

Watch your fingers! These magnets are easily stong enough so that you can put one on the palm of your hand, and another on the back of your hand, and they will hold themselves there, giving your hand a firmish pinch. When they get closer together than the thickness of your hand, they are powerful enough to give you a painful injury.

 

[Johnny Pneumatic]

I suppose you've all encountered the Levitron ?

I got one of these for Christmas. It really is amazing

Yet another science gadget I have to buy.

 

[rockoon]

bewareofdogmas, please remove the pictures and rehost them yourself. stealing other peoples bandwidith is a no-no.

It seems to me.. "rehosting" the image would be theft. Linking to the picture is not. Thats what the internet was designed to do.

 

[ceptimus]

bewareofdogmas, please remove the pictures and rehost them yourself. stealing other peoples bandwidith is a no-no.

He couldn't do it now, even if he agreed with you. The new anti-editing policy precludes this.