You will need
- Ferrofluid (we bought ours from first4magnets.com)
- Rare earth magnet (these are extremely strong magnets, usually made out of neodymium)
- Paper towels and cleaning materials
- A plate, or a large, washable table surface
Do not drink ferrofluid. Rare earth magnets are powerful! Do not swallow. Do not allow young children to play with them. Ferrofluid will stain, so protect skin and surfaces.
- Wearing your gloves, pour a little of the ferrofluid onto a plate or wipeable table surface (avoid woods that might stain).
- Place the rare earth magnet underneath the plate or table and watch the black liquid spring into life. Hedgehog-like spiky tufts will form directly above the magnet, following its movements as you slide it around the underside.
- Blow on it to watch the spikes spin! You can even make the ferrofluid crawl up surfaces and – if you don’t mind making a mess – hover the magnet over the surface to see it defy gravity by ‘dripping’ upwards onto the magnet, transforming it into an eerily squidgy, slimy black ball.
What’s going on?
A ferrofluid is an oily liquid blended with microscopic particles of metal. It is combined with a liquid ‘surfactant’ to prevent clumping. It forms such crazy shapes in the presence of a magnet because the metal particles try to align themselves along the path of the magnetic field.
You can buy small bottles of ferrofluid online for a few pounds, or you can try making your own by mixing a cupful of laser printer toner with a little cooking oil. Be aware that not all modern laser printer ink is magnetic, so only try it if you have some spare. Like black printer ink, all ferrofluids stain easily, so make sure that you wear gloves and be careful where you pour it. You may want to consider putting on an apron.
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