Remember my magnets show?

[athon]

I asked for some advice on various things you could demonstrate using magnets, for a show on the topic. That was about three months back.

Well, I've the past few months touring it. And for those who helped me, I'd like to thank you all for your advice. It was a huge success.

There were only a few demonstrations - one involving ping-pong balls for electrons, demonstrating electromagnetism. Another was a copper tube, demonstrating magnetic breaking. I made a 1.5 metre long gauss rifle and used it to shoot down a toy stormtrooper (well, I did have a Star Wars theme to the show...how else do you demonstrate, 'The Force'). I also made an electromagnet.

Maybe one day I'll get that rail gun working. That would be something.

Athon

 

[Soapy Sam]

Wot's magnetic breaking? (Or do you mean "braking", you quasi literate antipodean person?)


ETA- ps Don't suppose you made a video clip?

He may be your friend, but he's possibly my redneck third cousin. I have to keep an eye on him.

 

[Zep]

Hey! Stop kawling my frend a quasi! It's AUSSIE!!

 

[CFLarsen]

Hey! Stop kawling my frend a quasi! It's AUSSIE!!

"NeoDanish".

 

[Big Al]

At school, I made a linear induction motor, 1 slot/pole/phase, 1/3 chorded. Great fun! I learnt all sorts, starting with Earnshaw's Theorem (no array of permanent magnets is inherently self-supporting).

 

[Cuddles]

Wot's magnetic breaking?

It's the art of dropping magnets on the floor and then hoping that they weren't very expensive.

Maybe one day I'll get that rail gun working. That would be something.

If it doesn't shoot blue swirly lines out of it, it doesn't count.

 

[Soapy Sam]

It's the art of dropping magnets on the floor and then hoping that they weren't very expensive.

Could be. The really high Gauss rare earth ones do tend to be brittle. They can attract strongly enough to shatter on impact.

 

[Orangutan]

I learnt all sorts, starting with Earnshaw's Theorem (no array of permanent magnets is inherently self-supporting).

O RLY?

http://www.kjmagnetics.com/products.asp?cat=85

There are, however, several exceptions to the rule's assumptions which allow magnetic levitation.

http://en.wikipedia.org/wiki/Magnetic_levitation

Edit: I have one of those, the pyrolytic graphite was no where near that thick on the one I got!

 

[Cuddles]

O RLY?

http://www.kjmagnetics.com/products.asp?cat=85



http://en.wikipedia.org/wiki/Magnetic_levitation

Edit: I have one of those, the pyrolytic graphite was no where near that thick on the one I got!

They aren't self-supporting, they are resting on a table.

http://en.wikipedia.org/wiki/Earnshaw's_theorem

 

[Orangutan]

They aren't self-supporting, they are resting on a table.

http://en.wikipedia.org/wiki/Earnshaw's_theorem

Look at the first link I posted, that shows a magnet levitating. It's cheating as it's using a diamagnetic material which Earnshaw's theorem does not take account of. In fact from the article you linked to:

There are, however, several exceptions to the rule's assumptions which allow magnetic levitation.

If you were kidding my apologies I didn't see a smilie so I wasn't sure.

 

[Cuddles]

Look at the first link I posted, that shows a magnet levitating. It's cheating as it's using a diamagnetic material which Earnshaw's theorem does not take account of. In fact from the article you linked to:

If you were kidding my apologies I didn't see a smilie so I wasn't sure.

Well I wasn't kidding, but I may have misunderstood slightly. I took the orgininal statement that "no array of permanent magnets is inherently self-supporting" to mean in free space. If gravity is a factor then of course it all makes sense.

 

[Big Al]

It essentially says that you can't do seady levitation tricks with permanent magnets and nothing else, the way you can with rotating electromagnetic fields. Diamagnetics are another consideration.