Magnetic levitation and ferrofluid

I made this video to demonstrate how you can levitate something using diamagnetism. The video is pretty self explanatory but leaves out some details...

The magnets are neodymium magnets. An alloy of the rare earth metal. They are incredibly strong.

The ferrofluid is a suspension of nano scale particles of magnetite, haematite or some other compound containing iron. The particles are suspended in a surfactant, which in my case is oleic acid (I think). The particles are kept in permanent suspension my Brownian motion. The fluid forms into points like iron filings would because of an effect called normal-field instability.

You can buy ferrofluid here. Or here for US.

You can buy pyrolytic graphite here. Or here for US.

You can buy neodymium cube magnets here. Or here for US.

Here are some pictures (click to enlarge):

Magnetic levitation and ferrofluid

Magnetic levitation and ferrofluid

Magnetic levitation and ferrofluid

Magnetic levitation and ferrofluid

You might also like these other posts about magnets.

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  • http://www.gemmaarrowsmith.com Gemma

    Wowza, those pictures are beautiful.

    • http://www.stevemould.com Steve Mould

      I love my Canon G10!

  • http://www.gemmaarrowsmith.com Gemma

    Wowza, those pictures are beautiful.

    • http://www.stevemould.com Steve Mould

      I love my Canon G10!

  • Matt

    how long will your home made ferro fluid last? I understand the surfactant ends up breaking down after a while so it stops being a colloidal suspension.

    • http://www.stevemould.com Steve Mould

      Mine isn’t home made. I bought it in November 2008 and I don’t notice any degradation. There are a few different kinds of surfactant used so I guess it depends.

  • Matt

    how long will your home made ferro fluid last? I understand the surfactant ends up breaking down after a while so it stops being a colloidal suspension.

    • http://www.stevemould.com Steve Mould

      Mine isn’t home made. I bought it in November 2008 and I don’t notice any degradation. There are a few different kinds of surfactant used so I guess it depends.

  • raivo

    very cool video and beautiful experiment.

    • http://www.stevemould.com Steve Mould

      Thanks Raivo.

  • raivo

    very cool video and beautiful experiment.

    • http://www.stevemould.com Steve Mould

      Thanks Raivo.

  • Rachael

    That stuff is flippin cool!

  • Rachael

    That stuff is flippin cool!

  • Richard Perry

    Hi Steve. Saw you at this years Cheltenham Science Festival. Great Communicator! Was just looking at this video and wondered where you got the magnetic cubes from. I've searched the net but have obviously been looking in the wrong places. Any help would be appreciated. Cheers, Richard.

  • steventhebrave

    Hey Richard. Thanks for the feedback. Cheltenham was so much fun.

    You can get the cube magnets here:

    http://shop.ebay.co.uk/i.html?_nkw=neodymium+cu

    That's the same size as the ones I have.

  • Maruthi

    can i levitate iron nails in electromagnetic levitator

    • http://blog.stevemould.com Steve Mould

      Iron is ferromagnetic which means that when you put it in a magnetic field it becomes a magnet too. But unlike the diamagnetic graphite in the video, it becomes a magnet in the SAME directing as the original magnet. That means that iron is ATTRACTED to a magnet not repelled from it. So you can’t levitate iron with a magnet!

  • http://twitter.com/irskep Steve Johnson

    Why are you ripping off the Twitterific icon for your web site?

    • http://blog.stevemould.com Steve Mould

      I didn’t know I was. I got it from a website that had a load of twitter badges you could use. I guess it wasn’t legit! I’ll change it.

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  • EddyMorrisiya

    Ferrofluid is so much fun, a while ago i got a ferrofluid toy from and i love it!

    http://www.czferro.com