Bismuth like a Mirror or like a Sponge?

[alan2here]

As far as can understand Bismuth has the bizzare effect of reflecting magnetic feilds. This makes it usefull in levetation experments. Mirrors that reflect light are verry thin, however sponges that are verry thin would not stop me injuring myself verry well if I fell onto one. All pictures of Bismuth I have seen show it as a block. My question is weather a thin layer of Bismuth will work or weather a thick block is needed to get the effect. The reason I see this as important is because Bismuth is rather (very) expensive, and a large yet very thin layer of anything could be quite cheap.

[Gilded]

Bismuth is actually dirt cheap compared to another more diamagnetic material, namely pyrolytic graphite. Bismuth isn't diamagnetic enough for a thin sheet to suffice for commercial-grade magnet levitating, but that doesn't really matter as it really doesn't cost that much.

[YT2095]

I have a rather larrge chunk of 99.99% pure Bi metal here, and although it will easily melt and reasonably thin plates can be made with patience, it`s so Extremely brittle that if you DID fall on it you`de still get hurt anyway, as it would shatter!

[alan2here]

I was wondering about using it to form a levatation rink. Like an Ice Rink but with 4 magnets in each shoe you have to wear and a large surface of a diamagnetic material underneeth you'r feet. Like ice skateing but without the friction. (alternitivly hover go-carts)

[YT2095]

that`s a bit dumb (if you`ll excuse the expression).

 

How do you plan on doing anything other than a straight Line if there`s no friction?

[alan2here]

Hmm. I didn't think of that.

 

Maybe a block, fairly thin and big enough to lie on you'r front on. With two small fans in small tubes (one at each front corner). Which rotate and could be turned with you'r hands. Being a hover vehicle the track could contain small drops, jumps, concave and convex bits etc... and as long as you didn't land right onto one side or upside down or from too much of a hight it should always be a verry smooth ride.

[alan2here]

Actually you wouldn't need much underneeth you, the block dosn't have to do anything but hold the magnets on each of it's corners and bend a bit in the middle, alternitivle they could just be attached to you'r hands\feet\middle and the propultion be conected you you'r back, and the throttle could be controlled by a hand. I think a larger vehicle would have less point, this would feel more like flying. only you wouldn't leave the ground more than a meter or so.

[YT2095]

a magnet strong enough to do that would screw up most engines badly, thats if you`re feet didn`t get stuck to the engine on your back forcing you into a rather awkward position.

[Gilded]

I'm not sure if you could even build a rink like that without taking advantage of superconductors and/or powerful electromagnets.

[alan2here]

I was thinking neodymium magnets.

 

Any yes, the electric motor would have to contain sevral matal compenents and batteries (also made of some metal).

 

Why not just make the casings for the motor\battery's out of a diamagnetic materal and make the fans blades out of plastic?

 

I can still think that crashing into someone else and getting stuck to them could be a problem, Im shure that slight issue could be overcome.

[Rocket Man]

get an ac magnet and a thin-ish copper floor. magnetic feild builds up in the floor to oppose the boot, by the time ohmic heating has taken over, the boot has reversed polarity and induced a current. you could come up with some funky electronics to sense motion and apply a retarding force to lateral motion if you had enough control over the feild.

this sort of thing would end up with you using much the same technique as inline skates on glass with viscous lubrication

[alan2here]

That sounds impresivly power consuming.

[Rocket Man]

That sounds impresivly power consuming.

 

oh yes, nothing a direct feed from the local grid can't handle...

actually, there are a few unfesable designs like this to make a maglev train. when a suitably powerful permanent magnet moves quickly over copper or aluminium, you get a repulsive force. so if you get the train moving fast enough (several times the speed of sound), levitation is a direct result of motion. however, a lot of energy is absorbed by the rails by ohmic heating and forward force is a big issue

[insane_alien]

oh yes, nothing a direct feed from the local grid can't handle...

actually, there are a few unfesable designs like this to make a maglev train. when a suitably powerful permanent magnet moves quickly over copper or aluminium, you get a repulsive force. so if you get the train moving fast enough (several times the speed of sound), levitation is a direct result of motion. however, a lot of energy is absorbed by the rails by ohmic heating and forward force is a big issue

 

if its unfeasable anyway i propose that we strap a few saturn-V boosters to it. forward force? you got it.

[alan2here]

I think I prefer my way, I can probbebly do it with just a coupple of AA battery's. It would be harder to get a power station to fit onto the board without making it too heavy.

[alan2here]

To answer my own question from my embarrassingly uninformed past self the sponge apology is more accurate.

[DivideByZero]

wouldn't wearing those 4 blocks of magnets under you feet on a magnetic rink hurt your feet? The opposite pole of the magnet would overcome your feet's manipulative skills if you tilt you feet just a bit.

[big314mp]

Perhaps a board of some sort? I'm imagining a hill that one could sled down.

[qlue]

A simple hovercraft can be made to float on a magnetic floor. The floor is constructed from alternate magnets in a checkerboard pattern. The hovercraft uses three or more electro magnets with hall effect sensors to provide feedback. The control circuit works to cancel the magnetic field detected by the sensors.